A343987 - OEIS

%I #19 May 10 2024 02:16:37

%S 5105,5131,5616,5859,6435,6883,7777,9315,9737,9793,10017,10250,10458,

%T 10936,10962,11000,11060,11088,11592,11664,11781,12168,12229,12285,

%U 12320,12385,12392,12411,12707,13104,13384,13734,13832,13904,13923,14112,14183,14239,14581,14833,14896,14904,15176,15561,15596

%N Numbers that are the sum of four positive cubes in five or more ways.

%H David Consiglio, Jr., <a href="/A343987/b343987.txt">Table of n, a(n) for n = 1..20000</a>

%e 5616 = 1^3 + 8^3 + 12^3 + 15^3

%e      = 2^3 + 8^3 + 10^3 + 16^3

%e      = 4^3 + 4^3 + 14^3 + 14^3

%e      = 4^3 + 5^3 + 11^3 + 16^3

%e      = 8^3 + 9^3 + 10^3 + 15^3

%e so 5616 is a term.

%o (Python)

%o from itertools import combinations_with_replacement as cwr

%o from collections import defaultdict

%o keep = defaultdict(lambda: 0)

%o power_terms = [x ** 3 for x in range(1, 50)]

%o for pos in cwr(power_terms, 4):

%o     tot = sum(pos)

%o     keep[tot] += 1

%o rets = sorted([k for k, v in keep.items() if v >= 5])

%o for x in range(len(rets)):

%o     print(rets[x], end=", ")

%Y Cf. A025370, A343967, A343971, A343986, A343989, A344356, A345148.

%K nonn

%O 1,1

%A _David Consiglio, Jr._, May 06 2021