OFFSET
1,1
COMMENTS
Corresponding square pyramidal numbers are 5, 650, 4900, 5525, 6201, 38024, 42925, 73810, 132349, 137825, 299536, 308945, 583220, 597861, 612745, 1026745, ...
EXAMPLE
12 is a term because A000330(12) = 1^2 + 2^2 + ... + 11^2 + 12^2 = 650 = 5^2 + 25^2.
MATHEMATICA
Select[Range@ 1000, SquaresR[2, Binomial[# + 2, 3] + Binomial[# + 1, 3]] > 0 &] (* Michael De Vlieger, Mar 06 2016 *)
PROG
(PARI) isA000404(n) = {for( i=1, #n=factor(n)~%4, n[1, i]==3 && n[2, i]%2 && return); n && ( vecmin(n[1, ])==1 || (n[1, 1]==2 && n[2, 1]%2)); }
for(n=0, 1e3, if(isA000404(n*(n+1)*(2*n+1)/6), print1(n, ", ")));
CROSSREFS
KEYWORD
nonn
AUTHOR
Altug Alkan, Mar 06 2016
STATUS
approved