A374424 - OEIS

A374424

a(n) is the smallest number which can be represented as the sum of 4 distinct positive n-th powers in exactly 2 ways, or -1 if no such number exists.

%I #7 Jul 19 2024 19:14:34

%S 12,90,1036,6834,4062500,160426515,2056364173794800

%N a(n) is the smallest number which can be represented as the sum of 4 distinct positive n-th powers in exactly 2 ways, or -1 if no such number exists.

%e a(5) = 4062500 = 1^5 + 14^5 + 16^5 + 19^5 = 5^5 + 10^5 + 15^5 + 20^5.

%e a(6) = 160426515 = 1^6 + 3^6 + 19^6 + 22^6 = 1^6 + 10^6 + 15^6 + 23^6.

%Y Cf. A046881, A374418, A374421, A374422, A374423, A374425.

%K nonn,hard,more

%O 1,1

%A _Ilya Gutkovskiy_, Jul 08 2024

%E a(7) from _Michael S. Branicky_, Jul 09 2024