cp's OEIS Frontend

A025300 Numbers that are the sum of 2 nonzero squares in 9 or more ways.

%I A025300 #18 Jun 01 2025 14:20:08
%S A025300 71825,93925,122525,138125,143650,156325,160225,173225,187850,204425,
%T A025300 209525,223925,226525,235625,244205,245050,257725,267325,273325,
%U A025300 276250,287300,292825,296225,300625,308125,308425,312650,320450,333125,337025
%N A025300 Numbers that are the sum of 2 nonzero squares in 9 or more ways.
%H A025300 Robert Israel, <a href="/A025300/b025300.txt">Table of n, a(n) for n = 1..10000</a>
%H A025300 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%p A025300 N:= 4*10^5: # generate all entries <=N
%p A025300 V:= Vector(N,datatype=integer[4]):
%p A025300 for a from 1 to floor(sqrt(N)) do
%p A025300   for b from a do
%p A025300     n:= a^2 + b^2;
%p A025300     if n > N then break fi;
%p A025300     V[n]:= V[n]+1
%p A025300 od od:
%p A025300 select(t -> V[t] >= 9, [$1..N]); # _Robert Israel_, Jun 01 2025
%t A025300 nn = 337025; 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, _?(# >= 9 &)]] (* _T. D. Noe_, Apr 07 2011 *)
%Y A025300 Cf. A025292, A025299, A025301, A025337.
%K A025300 nonn
%O A025300 1,1
%A A025300 _David W. Wilson_