OFFSET
3,1
LINKS
Michel Marcus, Table of n, a(n) for n = 3..10000
EXAMPLE
6 is a triangular and hexagonal number, so a(6) = 3 + 6 = 9.
PROG
(PARI) a(n) = sum(k=3, n, if (ispolygonal(n, k), k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Mar 21 2021
STATUS
approved