A345523 Numbers that are the sum of seven cubes in five or more ways.

627, 768, 838, 845, 857, 864, 874, 881, 894, 900, 920, 937, 950, 955, 962, 969, 976, 981, 983, 990, 1002, 1009, 1011, 1016, 1027, 1046, 1053, 1054, 1060, 1061, 1063, 1072, 1079, 1089, 1096, 1098, 1102, 1105, 1107, 1109, 1115, 1117, 1121, 1124, 1128, 1133

Offset

1,1

Links

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

Example

768 is a term because 768 = 1^3 + 1^3 + 1^3 + 1^3 + 2^3 + 3^3 + 8^3 = 1^3 + 1^3 + 1^3 + 3^3 + 3^3 + 4^3 + 7^3 = 1^3 + 1^3 + 2^3 + 2^3 + 3^3 + 6^3 + 6^3 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 5^3 + 7^3 = 3^3 + 3^3 + 3^3 + 3^3 + 3^3 + 5^3 + 6^3.

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 >= 5])
    for x in range(len(rets)):
        print(rets[x])

Crossrefs

Cf. A345482, A345514, A345522, A345524, A345535, A345571, A345777.

Sequence in context: A031638 A098262 A031523 * A345777 A129974 A031703

Adjacent sequences: A345520 A345521 A345522 * A345524 A345525 A345526

Keyword

nonn

Author

David Consiglio, Jr., Jun 20 2021

Status

approved