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A345813 Numbers that are the sum of six fourth powers in exactly one ways. 6

%I #6 Jul 31 2021 21:57:09

%S 6,21,36,51,66,81,86,96,101,116,131,146,161,166,181,196,211,226,246,

%T 306,321,326,336,371,386,401,406,436,451,466,486,501,546,561,576,581,

%U 611,626,630,641,645,660,661,675,676,690,691,705,706,710,725,740,755,756

%N Numbers that are the sum of six fourth powers in exactly one ways.

%C Differs from A003340 at term 20 because 261 = 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 4^4 = 1^4 + 1^4 + 2^4 + 3^4 + 3^4 + 3^4.

%H Sean A. Irvine, <a href="/A345813/b345813.txt">Table of n, a(n) for n = 1..10000</a>

%e 21 is a term because 21 = 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 2^4.

%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, 6):

%o tot = sum(pos)

%o keep[tot] += 1

%o rets = sorted([k for k, v in keep.items() if v == 1])

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

%o print(rets[x])

%Y Cf. A003340, A048929, A344190, A345814, A345823, A346356.

%K nonn

%O 1,1

%A _David Consiglio, Jr._, Jun 26 2021

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Last modified March 29 05:28 EDT 2024. Contains 371264 sequences. (Running on oeis4.)