A116039 Numbers k such that k + prime(k) + prime(prime(k)) is a semiprime (A001358).

1, 2, 8, 9, 11, 12, 18, 19, 22, 23, 26, 29, 33, 35, 43, 47, 50, 53, 57, 59, 61, 69, 75, 76, 77, 78, 81, 89, 103, 105, 109, 112, 124, 125, 131, 135, 140, 141, 142, 143, 146, 151, 153, 155, 160, 166, 170, 175, 176, 177, 181, 189, 209, 211, 215, 216, 220, 225, 226

Offset: 1

Author

Giovanni Resta, Feb 13 2006

Keywords

• nonn

Examples

			112 is in the sequence since 112 + prime(112) + prime(prime(112)) = 5242 = 2*2621.
		

Links

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

Crossrefs

Cf. A001358, A116038.

Programs

Maple

with(numtheory): A116039:=n->`if`(bigomega(n+ithprime(n)+ithprime(ithprime(n))) = 2, n, NULL): seq(A116039(n), n=1..500); # Wesley Ivan Hurt, Jun 23 2015