

A276680


Number of divisors of the nth heptagonal number.


6



1, 2, 6, 4, 4, 5, 10, 6, 8, 4, 8, 12, 4, 4, 24, 16, 4, 8, 8, 8, 12, 4, 16, 24, 6, 4, 20, 8, 4, 18, 12, 10, 12, 4, 16, 16, 8, 8, 36, 12, 4, 16, 8, 16, 16, 4, 12, 24, 9, 12, 32, 8, 4, 10, 32, 12, 12, 8, 8, 40, 4, 4, 48, 12, 16, 12, 8, 8, 16, 8, 20, 48, 4, 4
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OFFSET

1,2


LINKS



FORMULA



EXAMPLE

a(3) = 6 because the 3rd heptagonal number is 18, which has 6 divisors: 1,2,3,6,9,18.


MATHEMATICA

DivisorSigma[0, PolygonalNumber[7, Range[80]]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 09 2017 *)


PROG

(PARI)
pg(m, n) = (n^2*(m2)n*(m4))/2 \\ nth mgonal number
vector(100, n, numdiv(pg(7, n)))


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



