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A375331
a(n) is the smallest number which can be represented as the sum of 4 distinct positive n-th powers in exactly 4 ways, or -1 if no such number exists.
5
-1, 142, 4445, 300834
OFFSET
1,2
EXAMPLE
a(4) = 300834 = 1^4 + 4^4 + 12^4 + 23^4
= 1^4 + 16^4 + 18^4 + 19^4
= 3^4 + 6^4 + 18^4 + 21^4
= 7^4 + 14^4 + 16^4 + 21^4.
KEYWORD
sign,hard,more
AUTHOR
Ilya Gutkovskiy, Aug 12 2024
STATUS
approved