A345520 Numbers that are the sum of seven cubes in two or more ways.

131, 159, 166, 173, 185, 192, 211, 222, 229, 236, 243, 248, 255, 257, 262, 264, 269, 274, 276, 281, 283, 285, 288, 290, 292, 295, 299, 300, 302, 307, 309, 311, 314, 318, 320, 321, 325, 332, 333, 337, 339, 340, 344, 346, 348, 351, 353, 355, 358, 359, 360, 363

Offset

1,1

Links

Sean A. Irvine, Table of n, a(n) for n = 1..10000

Example

159 is a term because 159 = 1^3 + 1^3 + 1^3 + 1^3 + 3^3 + 3^3 + 3^3 = 1^3 + 1^3 + 2^3 + 2^3 + 2^3 + 2^3 + 4^3.

Prog

(Python)
from itertools import combinations_with_replacement as cwr
from collections import defaultdict
keep = defaultdict(lambda: 0)
power_terms = [x**3 for x in range(1, 1000)]
for pos in cwr(power_terms, 7):
    tot = sum(pos)
    keep[tot] += 1
    rets = sorted([k for k, v in keep.items() if v >= 2])
    for x in range(len(rets)):
        print(rets[x])

Crossrefs

Cf. A003330, A345479, A345511, A345521, A345532, A345568, A345774.

Sequence in context: A155924 A270237 A090264 * A345774 A132254 A087832

Adjacent sequences: A345517 A345518 A345519 * A345521 A345522 A345523

Keyword

nonn

Author

David Consiglio, Jr., Jun 20 2021

Status

approved