A345804 Numbers that are the sum of ten cubes in exactly two ways.

73, 80, 99, 134, 136, 141, 148, 155, 160, 162, 167, 169, 174, 176, 183, 186, 188, 190, 192, 193, 195, 199, 202, 204, 206, 209, 211, 212, 213, 214, 216, 218, 221, 223, 228, 230, 235, 240, 244, 247, 249, 254, 262, 266, 269, 270, 273, 274, 290, 292, 297, 304

Offset

1,1

Comments

Differs from A345550 at term 22 because 197 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 4^3 + 5^3 = 1^3 + 1^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 3^3 + 4^3 + 4^3 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 5^3.

Likely finite.

Links

Sean A. Irvine, Table of n, a(n) for n = 1..90

Example

80 is a term because 80 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 2^3 + 3^3 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3.

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, 10):
    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. A345550, A345794, A345803, A345805, A345854.

Sequence in context: A180558 A260555 A345550 * A064667 A217237 A075588

Adjacent sequences: A345801 A345802 A345803 * A345805 A345806 A345807

Keyword

nonn

Author

David Consiglio, Jr., Jun 26 2021

Status

approved