A345561 Numbers that are the sum of six fourth powers in four or more ways.

6626, 6691, 6866, 9251, 9491, 10115, 10706, 10786, 11555, 12595, 14225, 14691, 14771, 15315, 15330, 15395, 15570, 16051, 16595, 16610, 16660, 16675, 16850, 17090, 17091, 17236, 17316, 17331, 17346, 17860, 17875, 17940, 17955, 18195, 18786, 18851, 18866, 19155

Offset

1,1

Links

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

Example

6691 is a term because 6691 = 1^4 + 1^4 + 1^4 + 6^4 + 6^4 + 8^4 = 1^4 + 2^4 + 2^4 + 2^4 + 3^4 + 9^4 = 2^4 + 2^4 + 3^4 + 3^4 + 7^4 + 8^4 = 3^4 + 4^4 + 4^4 + 6^4 + 7^4 + 7^4.

Prog

(Python)
from itertools import combinations_with_replacement as cwr
from collections import defaultdict
keep = defaultdict(lambda: 0)
power_terms = [x**4 for x in range(1, 1000)]
for pos in cwr(power_terms, 6):
    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. A344354, A345513, A345560, A345562, A345570, A345718, A345816.

Sequence in context: A178213 A237320 A237726 * A345816 A250539 A251796

Adjacent sequences: A345558 A345559 A345560 * A345562 A345563 A345564

Keyword

nonn

Author

David Consiglio, Jr., Jun 20 2021

Status

approved