A345150 - OEIS

%I #7 Aug 05 2021 15:27:29

%S 13104,18928,19376,20755,21203,21896,22743,24544,24570,24787,25172,

%T 25928,27720,27755,27846,28917,29582,30429,31031,31248,31339,31402,

%U 31528,32858,33579,34056,34624,34713,34776,35289,35317,35441,35497,35712,36162,36190,36225

%N Numbers that are the sum of four third powers in seven or more ways.

%H David Consiglio, Jr., <a href="/A345150/b345150.txt">Table of n, a(n) for n = 1..10000</a>

%e 13104 is a term because 13104 = 1^3 + 10^3 + 16^3 + 18^3  = 1^3 + 11^3 + 14^3 + 19^3  = 2^3 + 9^3 + 15^3 + 19^3  = 4^3 + 6^3 + 14^3 + 20^3  = 4^3 + 9^3 + 10^3 + 21^3  = 5^3 + 7^3 + 11^3 + 21^3  = 8^3 + 9^3 + 14^3 + 19^3.

%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, 1000)]

%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 >= 7])

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

%o     print(rets[x])

%Y Cf. A025372, A344922, A345086, A345148, A345151, A345152, A345180.

%K nonn

%O 1,1

%A _David Consiglio, Jr._, Jun 09 2021