A345572 - OEIS

%I #6 Jul 31 2021 17:58:05

%S 10787,15396,15411,15586,15651,16611,16626,16676,16691,16866,17347,

%T 17956,17971,18867,19156,19236,19251,19411,19426,19491,19666,20035,

%U 20706,20771,21012,21187,21252,21267,21332,21397,21412,21442,21492,21507,21572,21621,21636

%N Numbers that are the sum of seven fourth powers in six or more ways.

%H Sean A. Irvine, <a href="/A345572/b345572.txt">Table of n, a(n) for n = 1..10000</a>

%e 15396 is a term because 15396 = 1^4 + 1^4 + 1^4 + 1^4 + 6^4 + 8^4 + 10^4 = 1^4 + 1^4 + 2^4 + 5^4 + 8^4 + 8^4 + 9^4 = 1^4 + 2^4 + 2^4 + 2^4 + 3^4 + 5^4 + 11^4 = 1^4 + 3^4 + 4^4 + 4^4 + 7^4 + 7^4 + 10^4 = 1^4 + 3^4 + 5^4 + 7^4 + 8^4 + 8^4 + 8^4 = 2^4 + 3^4 + 4^4 + 5^4 + 6^4 + 9^4 + 9^4.

%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, 7):

%o     tot = sum(pos)

%o     keep[tot] += 1

%o     rets = sorted([k for k, v in keep.items() if v >= 6])

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

%o         print(rets[x])

%Y Cf. A345524, A345563, A345571, A345573, A345581, A345609, A345828.

%K nonn

%O 1,1

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