OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
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*(m-2)-n*(m-4))/2 \\ n-th m-gonal number
vector(100, n, numdiv(pg(7, n)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Colin Barker, Sep 13 2016
STATUS
approved