OFFSET
0,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..10000
EXAMPLE
10, 15 are in interval ]9, 16] , a(4) = 2.
PROG
(PARI) a(n) = if (n, sum(i=(n-1)^2+1, n^2, ispolygonal(i, 3)), 1); \\ Michel Marcus, Nov 12 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Mar 08 2013
STATUS
approved