OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Square Pyramidal Number
MAPLE
M:= 20: # to get all terms <= A000330(M)
sqp:= [seq(k*(k+1)*(2*k+1)/6, k=1..M)]:
sort(convert(select(`<=`, {seq(seq(sqp[i]+sqp[j], j=1..i), i=1..M-1)}, sqp[M]), list)); # Robert Israel, Jun 12 2017
MATHEMATICA
nmax = 700; f[x_] := Sum[x^(k (k + 1) (2 k + 1)/6), {k, 1, 20}]^2; Exponent[#, x] & /@ List @@ Normal[Series[f[x], {x, 0, nmax}]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jun 12 2017
STATUS
approved