This is the only common year with three occurrences of Friday the 13th: those three in this common year occur in February, March, and November. Leap years starting on Sunday share this characteristic, for the months January, April and July. From February until March in this type of year is also the shortest period (one month) that runs between two instances of Friday the 13th.
Calendars
Calendar for any common year starting on Thursday, presented as common in many English-speaking areas
January
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
February
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
March
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
April
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
May
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
June
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
July
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
August
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
September
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
October
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
November
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
December
Su
Mo
Tu
We
Th
Fr
Sa
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
ISO 8601-conformant calendar with week numbers for any common year starting on Thursday (dominical letter D)
January
Wk
Mo
Tu
We
Th
Fr
Sa
Su
01
01
02
03
04
02
05
06
07
08
09
10
11
03
12
13
14
15
16
17
18
04
19
20
21
22
23
24
25
05
26
27
28
29
30
31
February
Wk
Mo
Tu
We
Th
Fr
Sa
Su
05
01
06
02
03
04
05
06
07
08
07
09
10
11
12
13
14
15
08
16
17
18
19
20
21
22
09
23
24
25
26
27
28
March
Wk
Mo
Tu
We
Th
Fr
Sa
Su
09
01
10
02
03
04
05
06
07
08
11
09
10
11
12
13
14
15
12
16
17
18
19
20
21
22
13
23
24
25
26
27
28
29
14
30
31
April
Wk
Mo
Tu
We
Th
Fr
Sa
Su
14
01
02
03
04
05
15
06
07
08
09
10
11
12
16
13
14
15
16
17
18
19
17
20
21
22
23
24
25
26
18
27
28
29
30
May
Wk
Mo
Tu
We
Th
Fr
Sa
Su
18
01
02
03
19
04
05
06
07
08
09
10
20
11
12
13
14
15
16
17
21
18
19
20
21
22
23
24
22
25
26
27
28
29
30
31
June
Wk
Mo
Tu
We
Th
Fr
Sa
Su
23
01
02
03
04
05
06
07
24
08
09
10
11
12
13
14
25
15
16
17
18
19
20
21
26
22
23
24
25
26
27
28
27
29
30
July
Wk
Mo
Tu
We
Th
Fr
Sa
Su
27
01
02
03
04
05
28
06
07
08
09
10
11
12
29
13
14
15
16
17
18
19
30
20
21
22
23
24
25
26
31
27
28
29
30
31
August
Wk
Mo
Tu
We
Th
Fr
Sa
Su
31
01
02
32
03
04
05
06
07
08
09
33
10
11
12
13
14
15
16
34
17
18
19
20
21
22
23
35
24
25
26
27
28
29
30
36
31
September
Wk
Mo
Tu
We
Th
Fr
Sa
Su
36
01
02
03
04
05
06
37
07
08
09
10
11
12
13
38
14
15
16
17
18
19
20
39
21
22
23
24
25
26
27
40
28
29
30
October
Wk
Mo
Tu
We
Th
Fr
Sa
Su
40
01
02
03
04
41
05
06
07
08
09
10
11
42
12
13
14
15
16
17
18
43
19
20
21
22
23
24
25
44
26
27
28
29
30
31
November
Wk
Mo
Tu
We
Th
Fr
Sa
Su
44
01
45
02
03
04
05
06
07
08
46
09
10
11
12
13
14
15
47
16
17
18
19
20
21
22
48
23
24
25
26
27
28
29
49
30
December
Wk
Mo
Tu
We
Th
Fr
Sa
Su
49
01
02
03
04
05
06
50
07
08
09
10
11
12
13
51
14
15
16
17
18
19
20
52
21
22
23
24
25
26
27
53
28
29
30
31
Applicable years
Gregorian Calendar
In the (currently used) Gregorian calendar, alongside Tuesday, the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-four common years per cycle or exactly 11% start on a Thursday. The 28-year sub-cycle only spans across century years divisible by 400, e.g. 1600, 2000, and 2400.
In the now-obsolete Julian calendar, the fourteen types of year (seven common, seven leap) repeat in a 28-year cycle (1461 weeks). A leap year has two adjoining dominical letters (one for January and February and the other for March to December, as 29 February has no letter). This sequence occurs exactly once within a cycle, and every common letter thrice.
As the Julian calendar repeats after 28 years that means it will also repeat after 700 years, i.e. 25 cycles. The year's position in the cycle is given by the formula ((year + 8) mod 28) + 1). Years 3, 14 and 20 of the cycle are common years beginning on Thursday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Thursday.
Labour Day falls on its latest possible date, September 7 – this is the only common year when Victoria Day and Labour Day are sixteen weeks apart (they are fifteen weeks apart in all other common years)
Labor Day falls on its latest possible date, September 7 – this is the only common year when Memorial Day and Labor Day are fifteen weeks apart (they are fourteen weeks apart in all other common years)