A344923 Numbers that are the sum of four fourth powers in exactly seven ways.

6576339, 16020018, 16408434, 22673634, 23056803, 33734834, 39786098, 43583138, 51071619, 52652754, 53731458, 57976083, 63985314, 64365939, 67655779, 68846274, 73744563, 75951138, 77495778, 87038883, 88648914, 89148114, 90665058, 90818898, 92800178, 93830803

Offset

1,1

Comments

Differs from A344922 at term 2 because 13155858 = 1^4 + 16^4 + 19^4 + 60^4 = 3^4 + 6^4 + 21^4 + 60^4 = 10^4 + 18^4 + 31^4 + 59^4 = 12^4 + 27^4 + 45^4 + 54^4 = 15^4 + 44^4 + 46^4 + 47^4 = 18^4 + 25^4 + 41^4 + 56^4 = 29^4 + 30^4 + 44^4 + 53^4 = 35^4 + 36^4 + 38^4 + 53^4.

Links

David Consiglio, Jr., Table of n, a(n) for n = 1..100

Example

6576339 is a term because 6576339 = 1^4 + 24^4 + 41^4 + 43^4  = 3^4 + 7^4 + 41^4 + 44^4  = 4^4 + 23^4 + 27^4 + 49^4  = 6^4 + 31^4 + 41^4 + 41^4  = 7^4 + 11^4 + 36^4 + 47^4  = 7^4 + 21^4 + 28^4 + 49^4  = 12^4 + 17^4 + 29^4 + 49^4.

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, 4):
    tot = sum(pos)
    keep[tot] += 1
rets = sorted([k for k, v in keep.items() if v == 7])
for x in range(len(rets)):
    print(rets[x])

Crossrefs

Cf. A344730, A344921, A344922, A344925, A344943, A345151.

Sequence in context: A257016 A234090 A344922 * A204404 A266914 A234711

Adjacent sequences: A344920 A344921 A344922 * A344924 A344925 A344926

Keyword

nonn

Author

David Consiglio, Jr., Jun 02 2021

Status

approved