OFFSET
3,1
COMMENTS
a(8) = 736, a(9) = 969.
LINKS
Eric Weisstein's World of Mathematics, Polygonal Number
EXAMPLE
For n = 3: 1 + 6 + 21 = 3 + 10 + 15 = 28.
CROSSREFS
KEYWORD
nonn,bref,more,hard
AUTHOR
Ilya Gutkovskiy, May 23 2023
STATUS
approved