login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A375332
a(n) is the smallest number which can be represented as the sum of 5 distinct positive n-th powers in exactly 4 ways, or -1 if no such number exists.
5
-1, 151, 2465, 54994, 1386406515, 351060139210
OFFSET
1,2
EXAMPLE
a(4) = 54994 = 1^4 + 2^4 + 4^4 + 8^4 + 15^4
= 1^4 + 2^4 + 9^4 + 10^4 + 14^4
= 2^4 + 5^4 + 6^4 + 11^4 + 14^4
= 3^4 + 7^4 + 8^4 + 10^4 + 14^4.
KEYWORD
sign,hard,more
AUTHOR
Ilya Gutkovskiy, Aug 12 2024
EXTENSIONS
a(5)-a(6) from Michael S. Branicky, Aug 12 2024
STATUS
approved