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%I #16 Jan 25 2022 02:01:09
%S 2,3,6,129,107103,19562634,2433065908
%N a(n) is the least k such that Sum_{i=1..k} (i/prime(i))^n > 1.
%e a(2)=3 because 3 terms are needed for a sum > 1:
%e (1/2)^2 + (2/3)^2 < 1, but (1/2)^2 + (2/3)^2 + (3/5)^2 > 1.
%e a(3)=6 because 6 terms are needed for a sum > 1:
%e (1/2)^3 + (2/3)^3 + (3/5)^3 + (4/7)^3 + (5/11)^3 + (6/13)^3 > 1.
%Y Cf. A000040.
%K nonn,hard,more
%O 1,1
%A _Alex Ratushnyak_, Apr 12 2021
%E a(7) from _Daniel Suteu_, May 04 2021