65986domain: NAppears in sequencesa(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=a(2)=1 and a(3)=2.at n=20A024945Numbers k such that 2^k + 3^k is a semiprime.at n=34A050244G.f. satisfies: A(x) = 1/(1 - x/(1 - x*A(x))^3)^2.at n=7A161798Numbers k such that (2^k + 3^k)/13 is prime.at n=16A181628