55 (number)

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Mathematics[edit]

55 is the 10th Fibonacci number[1] and a triangular number (the sum of the consecutive numbers 1 to 10).[2] It is the largest Fibonacci number to also be a triangular number.

It is a square pyramidal number (the sum of the squares of the integers 1 to 5)[3] as well as a heptagonal number,[4] and a centered nonagonal number.[5]

In base 10, it is a Kaprekar number.[6]

55 is a semiprime, being the product of 5 and 11 and it is the 2nd member of the (5.q) semiprime family. 55 is one of only two integers with an aliquot sum of 17 (the other being 39). 55 has an aliquot sequence of 4 members: (55, 17, 1, 0).

Science[edit]

Astronomy[edit]

Music[edit]

  • A song produced by Group X was called "Schfifty Five".
  • The name of a song by British Indie Rock Band Kasabian. The song was released as a B side to Club Foot and was recorded live when the band performed at London's Brixton Academy.
  • I Can't Drive 55, a song by Sammy Hagar
  • Ol' '55, a song by Tom Waits
  • Cristian Vogel released an album in 2005 with the title "Station 55"
  • Ol' 55 (band), an Australian rock band.
  • Primer 55 an American band
  • 55 Cadillac, an album by Andrew W.K.

Transportation[edit]

Film[edit]

Years[edit]

Other uses[edit]

See also[edit]

References[edit]

  1. ^ "Sloane's A000045 : Fibonacci numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30. 
  2. ^ "Sloane's A000217 : Triangular numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30. 
  3. ^ "Sloane's A000330 : Square pyramidal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30. 
  4. ^ "Sloane's A000566 : Heptagonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30. 
  5. ^ "Sloane's A060544 : Centered 9-gonal (also known as nonagonal or enneagonal) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30. 
  6. ^ "Sloane's A006886 : Kaprekar numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.