%I #13 Nov 16 2023 15:56:50
%S 1,2,3,5,7,10,15,19,22,24,26,27,31,36,41,44,57,60,67,78,84,87,91,93,
%T 101,102,103,104,105,107,115,116,120,121,124,126,128,129,131,135,136,
%U 137,138,140,151,161,168,183,186,189,190,191,195,208,215,225,227,228,231
%N Numbers k such that k-th prime + k-th semiprime is semiprime.
%H Robert Israel, <a href="/A092021/b092021.txt">Table of n, a(n) for n = 1..10000</a>
%e 3 is a member because third prime is 5, third semiprime is 9 and 5+9=14 is semiprime.
%p P:= select(isprime, [2,seq(i,i=3..10000,2)]):
%p S:= select(t -> numtheory:-bigomega(t)=2, [$4..10000]):
%p select(t -> numtheory:-bigomega(P[t]+S[t]) = 2, [$1 .. min(nops(P), nops(S))]); # _Robert Israel_, Nov 15 2023
%Y Cf. A092108.
%K easy,nonn
%O 1,2
%A _Ray Chandler_, Feb 24 2004