A344192 Numbers that are the sum of three fourth powers in exactly two ways.

2673, 6578, 16562, 28593, 35378, 42768, 43218, 54977, 94178, 105248, 106353, 122018, 134162, 137633, 149058, 171138, 177042, 178737, 181202, 195122, 195858, 198497, 216513, 234273, 235298, 235553, 264113, 264992, 300833, 318402, 318882, 324818, 334802, 346673, 364658, 384833, 439922, 457488

Offset

1,1

Comments

Differs from A309762 at term 59 because 811538 = 4^4 + 23^4 + 27^4 = 7^4 + 21^4 + 28^4 = 12^4 + 17^4 + 29^4

Links

David Consiglio, Jr., Table of n, a(n) for n = 1..10000

Example

16562 is a member of this sequence because 16562 = 1^4 + 9^4 + 10^4 = 5^4 + 6^4 + 11^4

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, 50)]
for pos in cwr(power_terms, 3):
    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. A025396, A309762, A344188, A344193, A344240.

Sequence in context: A250855 A235253 A309762 * A345896 A085559 A123075

Adjacent sequences: A344189 A344190 A344191 * A344193 A344194 A344195

Keyword

nonn

Author

David Consiglio, Jr., May 11 2021

Status

approved