cp's OEIS Frontend

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

%I A025296 #18 Jun 01 2025 14:44:56
%S A025296 5525,8125,8450,9425,10625,11050,12025,12325,13325,14365,14450,15725,
%T A025296 16250,17225,17425,18125,18785,18850,19825,21125,21250,22100,22525,
%U A025296 23125,23725,24050,24505,24650,25625,25925,26650,26825,27625,28730,28925,29725
%N A025296 Numbers that are the sum of 2 nonzero squares in 5 or more ways.
%H A025296 Robert Israel, <a href="/A025296/b025296.txt">Table of n, a(n) for n = 1..10000</a>
%H A025296 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%p A025296 N:= 10^5: # generate all entries <=N
%p A025296 V:= Vector(N,datatype=integer[4]):
%p A025296 for a from 1 to floor(sqrt(N)) do
%p A025296   for b from a do
%p A025296     n:= a^2 + b^2;
%p A025296     if n > N then break fi;
%p A025296     V[n]:= V[n]+1
%p A025296 od od:
%p A025296 select(t -> V[t] >= 5, [$1..N]); # _Robert Israel_, Jun 01 2025
%t A025296 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 *)
%Y A025296 Cf. A025288, A025295, A025297, A025333, A051167.
%K A025296 nonn
%O A025296 1,1
%A A025296 _David W. Wilson_