A025296 Numbers that are the sum of 2 nonzero squares in 5 or more ways.

5525, 8125, 8450, 9425, 10625, 11050, 12025, 12325, 13325, 14365, 14450, 15725, 16250, 17225, 17425, 18125, 18785, 18850, 19825, 21125, 21250, 22100, 22525, 23125, 23725, 24050, 24505, 24650, 25625, 25925, 26650, 26825, 27625, 28730, 28925, 29725

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to sums of squares

Crossrefs

Cf. A025288, A025295, A025297, A025333, A051167.

Programs

Maple

N:= 10^5: # generate all entries <=N
V:= Vector(N,datatype=integer[4]):
for a from 1 to floor(sqrt(N)) do
  for b from a do
    n:= a^2 + b^2;
    if n > N then break fi;
    V[n]:= V[n]+1
od od:
select(t -> V[t] >= 5, [$1..N]); # Robert Israel, Jun 01 2025

Mathematica

nn = 30000; t = Table[0, {nn}]; lim = Floor[Sqrt[nn - 1]]; Do[num = i^2 + j^2; If[num <= nn, t[[num]]++], {i, lim}, {j, i}]; Flatten[Position[t, ?(# >= 5 &)]] (* _T. D. Noe, Apr 07 2011 *)