cp's OEIS Frontend

A025372 Numbers that are the sum of 4 nonzero squares in 7 or more ways.

%I A025372 #17 Aug 05 2021 07:27:34
%S A025372 130,135,138,148,150,154,162,170,172,175,178,180,182,183,186,187,189,
%T A025372 190,195,196,198,199,202,207,210,213,214,215,217,218,220,222,223,225,
%U A025372 226,228,229,230,231,234,235,237,238,242,243,244,245,246,247,250,252,253,255,258
%N A025372 Numbers that are the sum of 4 nonzero squares in 7 or more ways.
%H A025372 Robert Israel, <a href="/A025372/b025372.txt">Table of n, a(n) for n = 1..10000</a>
%H A025372 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%F A025372 {n: A025428(n) >= 7}. - _R. J. Mathar_, Jun 15 2018
%p A025372 N:= 1000: # for terms <= N
%p A025372 B:= Vector(N):
%p A025372 for i from 1 while 4*i^2 <= N do
%p A025372   for j from i while i^2 + 3*j^2 <= N do
%p A025372     for k from j while i^2 + j^2 + 2*k^2 <= N do
%p A025372       for l from k do
%p A025372         m:= i^2 + j^2 + k^2 + l^2;
%p A025372         if m > N then break fi;
%p A025372         B[m]:= B[m]+1
%p A025372 od od od od:
%p A025372 select(t -> B[t] >= 7, [$1..N]); # _Robert Israel_, Oct 23 2020
%Y A025372 Cf. A025335, A025363, A025371, A025373, A344800, A345150.
%K A025372 nonn
%O A025372 1,1
%A A025372 _David W. Wilson_