A345521 Numbers that are the sum of seven cubes in three or more ways.

222, 229, 248, 255, 262, 281, 283, 285, 318, 346, 370, 374, 377, 379, 381, 396, 400, 407, 412, 419, 426, 433, 437, 438, 444, 451, 463, 470, 472, 475, 477, 489, 494, 496, 501, 503, 505, 507, 510, 522, 529, 533, 536, 559, 564, 566, 568, 570, 577, 578, 584, 585

Offset

1,1

Links

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

Example

229 is a term because 229 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 2^3 + 5^3 = 1^3 + 1^3 + 2^3 + 3^3 + 3^3 + 3^3 + 3^3 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 3^3 + 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 >= 3])
    for x in range(len(rets)):
        print(rets[x])

Crossrefs

Cf. A345480, A345512, A345520, A345522, A345533, A345569, A345775.

Sequence in context: A092625 A043612 A371423 * A345775 A361628 A101955

Adjacent sequences: A345518 A345519 A345520 * A345522 A345523 A345524

Keyword

nonn

Author

David Consiglio, Jr., Jun 20 2021

Status

approved