%I #11 Oct 26 2015 22:41:01
%S 1,3,6,8,13,20,26,29,33,36,38,39,43,44,47,48,58,60,61,62,67,74,81,85,
%T 92,93,94,100,101,102,103,106,107,108,109,110,111,115,120,127,132,133,
%U 134,140,147,148,150,151,152,153,156,158,161,162,164,165
%N a(n) = smallest number > a(n-1) such that a(n-1) + a(n) is a semiprime (A001358), a(1)=1.
%C Similar sequences with any other initial a(1) will eventually merge with case a(1)=1.
%e 1 + 3 = 4 = 2*2, 3 + 6 = 9 = 3*3, 6 + 8 = 14 = 2*7, etc.
%t s={a=1};Do[k=a+1;While[PrimeOmega[a+k]!=2,k++];AppendTo[s,a=k],{100}];s
%o (PARI) lista(nn) = {print1(a = 1, ", "); for (k=1, nn, na = a+1; while (bigomega(a+na) != 2, na++); a = na; print1(a, ", "););} \\ _Michel Marcus_, Oct 17 2015
%Y Cf. A001358, A243625.
%K nonn
%O 1,2
%A _Zak Seidov_, Oct 15 2015