A345605 - OEIS

%I #6 Jul 31 2021 16:25:05

%S 4099,4130,4161,4341,4372,4583,5122,5153,5364,6145,7223,7254,7465,

%T 8246,10347,11874,11905,12116,12897,14998,19649,20905,20936,21147,

%U 21928,24029,28680,36866,36897,37108,37711,37889,39990,40138,44641,51393,51448,51479,51510

%N Numbers that are the sum of seven fifth powers in two or more ways.

%H Sean A. Irvine, <a href="/A345605/b345605.txt">Table of n, a(n) for n = 1..10000</a>

%e 4130 is a term because 4130 = 1^5 + 1^5 + 2^5 + 4^5 + 4^5 + 4^5 + 4^5 = 1^5 + 2^5 + 3^5 + 3^5 + 3^5 + 3^5 + 5^5.

%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**5 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 >= 2])

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

%o         print(rets[x])

%Y Cf. A003352, A345507, A345568, A345606, A345610, A346279.

%K nonn

%O 1,1

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