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 A345816 Numbers that are the sum of six fourth powers in exactly four ways. 8
 6626, 6691, 6866, 9251, 9491, 10115, 10706, 10786, 11555, 12595, 14225, 14691, 14771, 15315, 15330, 15570, 16051, 16595, 16660, 16675, 16850, 17090, 17091, 17236, 17316, 17331, 17346, 17860, 17875, 17940, 17955, 18195, 18786, 18851, 19155, 19170, 19475, 19490 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Differs from A345561 at term 16 because 15395 = 1^4 + 1^4 + 1^4 + 6^4 + 8^4 + 10^4 = 1^4 + 2^4 + 5^4 + 8^4 + 8^4 + 9^4 = 3^4 + 4^4 + 4^4 + 7^4 + 7^4 + 10^4 = 3^4 + 5^4 + 7^4 + 8^4 + 8^4 + 8^4 = 2^4 + 2^4 + 2^4 + 3^4 + 5^4 + 11^4. LINKS Sean A. Irvine, Table of n, a(n) for n = 1..10000 EXAMPLE 6691 is a term because 6691 = 1^4 + 1^4 + 1^4 + 6^4 + 6^4 + 8^4 = 1^4 + 2^4 + 2^4 + 2^4 + 3^4 + 9^4 = 2^4 + 2^4 + 3^4 + 3^4 + 7^4 + 8^4 = 3^4 + 4^4 + 4^4 + 6^4 + 7^4 + 7^4. MATHEMATICA Select[Range[20000], Count[PowersRepresentations[#, 6, 4], _?(#[[1]]>0&)]==4&] (* Harvey P. Dale, Mar 11 2023 *) PROG (Python) from itertools import combinations_with_replacement as cwr from collections import defaultdict keep = defaultdict(lambda: 0) power_terms = [x**4 for x in range(1, 1000)] for pos in cwr(power_terms, 6): tot = sum(pos) keep[tot] += 1 rets = sorted([k for k, v in keep.items() if v == 4]) for x in range(len(rets)): print(rets[x]) CROSSREFS Cf. A344355, A345561, A345766, A345815, A345817, A345826, A346359. Sequence in context: A237320 A237726 A345561 * A250539 A251796 A237794 Adjacent sequences: A345813 A345814 A345815 * A345817 A345818 A345819 KEYWORD nonn AUTHOR David Consiglio, Jr., Jun 26 2021 STATUS approved

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Last modified July 18 00:08 EDT 2024. Contains 374377 sequences. (Running on oeis4.)