OFFSET
1,3
COMMENTS
Squares in this sequence include a(1) = 0, a(2) = 1, a(5) = 16 and a(11) = 144. Are there any others?
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
A000330(4) = 1^2 + 2^2 + 3^2 + 4^2 = 30 so a(4) = (30 mod 1^2) + (30 mod 2^2) + (30 mod 3^2) + (30 mod 4^2) = 19.
MAPLE
f:= proc(n) local M, k;
M:= n*(n+1)*(2*n+1)/6;
add(M mod k^2, k=1..n)
end proc:
map(f, [$1..100]);
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, May 26 2021
STATUS
approved