A375334 - OEIS

%I #5 Aug 12 2024 13:11:43

%S -1,268,2835,49316,20301007,349717731

%N a(n) is the smallest number which can be represented as the sum of 7 distinct positive n-th powers in exactly 4 ways, or -1 if no such number exists.

%e a(6) = 349717731 = 2^6 + 6^6 +  7^6 + 17^6 + 20^6 + 22^6 + 23^6

%e                  = 2^6 + 8^6 + 10^6 + 11^6 + 16^6 + 21^6 + 25^6

%e                  = 5^6 + 8^6 + 10^6 + 11^6 + 14^6 + 23^6 + 24^6

%e                  = 5^6 + 8^6 + 13^6 + 14^6 + 15^6 + 16^6 + 26^6.

%Y Cf. A046881, A342901, A374418, A374421, A374422, A374423, A374424, A374425, A375329, A375330, A375331, A375332, A375333.

%K sign,hard,more

%O 1,2

%A _Ilya Gutkovskiy_, Aug 12 2024