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.
-1, 142, 4445, 300834
Offset: 1
Examples
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.