A343971 Numbers that are the sum of four positive cubes in four or more ways.

1979, 2737, 3663, 4384, 4445, 4474, 4949, 5105, 5131, 5257, 5320, 5473, 5499, 5553, 5616, 5733, 5768, 5833, 5852, 5859, 6064, 6104, 6328, 6372, 6435, 6587, 6643, 6832, 6883, 6912, 6974, 7000, 7030, 7120, 7217, 7371, 7560, 7686, 7777, 7840, 8099, 8108, 8281, 8316, 8344, 8379, 8414, 8505, 8568, 8927, 9016, 9018

Offset

1,1

Links

David Consiglio, Jr., Table of n, a(n) for n = 1..20000

Example

3663 = 1^3 + 10^3 + 11^3 + 11^3
     = 2^3 +  4^3 +  6^3 + 15^3
     = 2^3 +  9^3 +  9^3 + 13^3
     = 4^3 +  7^3 +  8^3 + 14^3
so 3663 is a term.

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, 50)]
for pos in cwr(power_terms, 4):
    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. A025369, A025407, A343968, A343972, A343987, A344034, A344352.

Sequence in context: A210160 A234179 A108510 * A343972 A225235 A289907

Adjacent sequences: A343968 A343969 A343970 * A343972 A343973 A343974

Keyword

nonn

Author

David Consiglio, Jr., May 05 2021

Status

approved