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A025371 Numbers that are the sum of 4 nonzero squares in 6 or more ways.

%I A025371 #16 Aug 05 2021 07:27:29
%S A025371 90,124,130,133,135,138,147,148,150,154,156,157,159,162,163,165,166,
%T A025371 170,171,172,174,175,177,178,180,182,183,186,187,188,189,190,193,195,
%U A025371 196,198,199,201,202,203,205,207,210,213,214,215,217,218,219,220,222,223,225,226
%N A025371 Numbers that are the sum of 4 nonzero squares in 6 or more ways.
%H A025371 Michael S. Branicky, <a href="/A025371/b025371.txt">Table of n, a(n) for n = 1..10000</a>
%H A025371 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%F A025371 {n: A025428(n) >= 6}. Union of A025372 and A025362. - _R. J. Mathar_, Jun 15 2018
%o A025371 (Python)
%o A025371 limit = 226
%o A025371 from functools import lru_cache
%o A025371 sq = [k**2 for k in range(1, int(limit**.5)+2) if k**2 + 3 <= limit]
%o A025371 sqs = set(sq)
%o A025371 @lru_cache(maxsize=None)
%o A025371 def findsums(n, m):
%o A025371   if m == 1: return {(n, )} if n in sqs else set()
%o A025371   return set(tuple(sorted(t+(s,))) for s in sqs for t in findsums(n-s, m-1))
%o A025371 print([n for n in range(4, limit+1) if len(findsums(n, 4)) >= 6]) # _Michael S. Branicky_, Apr 20 2021
%Y A025371 Cf. A025334, A025362, A025370, A025372, A344799, A345148.
%K A025371 nonn
%O A025371 1,1
%A A025371 _David W. Wilson_