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A345520 Numbers that are the sum of seven cubes in two or more ways.

%I A345520 #7 Aug 05 2021 15:22:15
%S A345520 131,159,166,173,185,192,211,222,229,236,243,248,255,257,262,264,269,
%T A345520 274,276,281,283,285,288,290,292,295,299,300,302,307,309,311,314,318,
%U A345520 320,321,325,332,333,337,339,340,344,346,348,351,353,355,358,359,360,363
%N A345520 Numbers that are the sum of seven cubes in two or more ways.
%H A345520 Sean A. Irvine, <a href="/A345520/b345520.txt">Table of n, a(n) for n = 1..10000</a>
%e A345520 159 is a term because 159 = 1^3 + 1^3 + 1^3 + 1^3 + 3^3 + 3^3 + 3^3 = 1^3 + 1^3 + 2^3 + 2^3 + 2^3 + 2^3 + 4^3.
%o A345520 (Python)
%o A345520 from itertools import combinations_with_replacement as cwr
%o A345520 from collections import defaultdict
%o A345520 keep = defaultdict(lambda: 0)
%o A345520 power_terms = [x**3 for x in range(1, 1000)]
%o A345520 for pos in cwr(power_terms, 7):
%o A345520     tot = sum(pos)
%o A345520     keep[tot] += 1
%o A345520     rets = sorted([k for k, v in keep.items() if v >= 2])
%o A345520     for x in range(len(rets)):
%o A345520         print(rets[x])
%Y A345520 Cf. A003330, A345479, A345511, A345521, A345532, A345568, A345774.
%K A345520 nonn
%O A345520 1,1
%A A345520 _David Consiglio, Jr._, Jun 20 2021