Centered heptagonal number
A centered heptagonal number is a centered figurate number that represents a heptagon with a dot in the center and all other dots surrounding the center dot in successive heptagonal layers. The centered heptagonal number for n is given by the formula
This can also be calculated by multiplying the triangular number for (n – 1) by 7, then adding 1.
The first few centered heptagonal numbers are
Centered heptagonal numbers alternate parity in the pattern odd-even-even-odd.
Centered heptagonal prime
A centered heptagonal prime is a centered heptagonal number that is prime. The first few centered heptagonal primes are
and centered heptagonal twin prime numbers are
- Regular heptagonal number.