A345586 - OEIS

%I #6 Jul 31 2021 17:38:42

%S 264,279,294,309,324,339,344,359,374,389,404,424,439,454,469,504,519,

%T 534,549,564,579,584,599,614,629,644,664,679,694,709,759,774,789,804,

%U 819,839,854,869,884,888,903,918,933,934,948,949,968,983,998,1013,1014

%N Numbers that are the sum of nine fourth powers in two or more ways.

%H Sean A. Irvine, <a href="/A345586/b345586.txt">Table of n, a(n) for n = 1..10000</a>

%e 279 is a term because 279 = 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 2^4 + 4^4 = 1^4 + 1^4 + 1^4 + 1^4 + 2^4 + 2^4 + 3^4 + 3^4 + 3^4.

%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**4 for x in range(1, 1000)]

%o for pos in cwr(power_terms, 9):

%o     tot = sum(pos)

%o     keep[tot] += 1

%o     rets = sorted([k for k, v in keep.items() if v >= 2])

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

%o         print(rets[x])

%Y Cf. A003343, A345541, A345577, A345587, A345595, A345619, A345844.

%K nonn

%O 1,1

%A _David Consiglio, Jr._, Jun 20 2021