A092021 Numbers k such that k-th prime + k-th semiprime is semiprime.

1, 2, 3, 5, 7, 10, 15, 19, 22, 24, 26, 27, 31, 36, 41, 44, 57, 60, 67, 78, 84, 87, 91, 93, 101, 102, 103, 104, 105, 107, 115, 116, 120, 121, 124, 126, 128, 129, 131, 135, 136, 137, 138, 140, 151, 161, 168, 183, 186, 189, 190, 191, 195, 208, 215, 225, 227, 228, 231

Offset: 1

Author

Ray Chandler, Feb 24 2004

Keywords

• easy
• nonn

Examples

			3 is a member because third prime is 5, third semiprime is 9 and 5+9=14 is semiprime.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A092108.

Programs

Maple

P:= select(isprime, [2,seq(i,i=3..10000,2)]):
S:= select(t -> numtheory:-bigomega(t)=2, [$4..10000]):
select(t -> numtheory:-bigomega(P[t]+S[t]) = 2, [$1 .. min(nops(P), nops(S))]); # Robert Israel, Nov 15 2023