OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Octagonal Number
EXAMPLE
From Seiichi Manyama, May 16 2021: (Start)
Let S(k, m) denote the sum of m octagonal numbers starting from k*(3*k-2). We have
a(1) = S(1, 1);
a(2) = S(19, 1) = S(1, 10);
a(3) = S(45, 1) = S(11, 9) = S(1, 18). (End)
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Ilya Gutkovskiy, Apr 12 2020
STATUS
approved