A175218 The third nonprimes after the primes.

8, 8, 9, 10, 15, 16, 21, 22, 26, 33, 34, 40, 45, 46, 50, 56, 63, 64, 70, 75, 76, 82, 86, 92, 100, 105, 106, 111, 112, 116, 130, 134, 141, 142, 153, 154, 160, 166, 170, 176, 183, 184, 195, 196, 201, 202, 214, 226, 231, 232, 236, 243, 244, 254, 260, 266, 273, 274

Offset: 1

Author

Jaroslav Krizek, Mar 06 2010

Keywords

• nonn

Examples

			prime(49) = 227, prime(50) = 229, therefore (228=1st, 230=2nd nonprime), 231 = a(49). - _Georg Fischer_, Oct 06 2024
		

Crossrefs

Cf. A175216, A175217, A175219, A175220.

Programs

PARI

a(n) = if(n<=2, 8, prime(n) + 2 + isprime(prime(n)+2) + 1) /* Georg Fischer, Oct 06 2024 */

Formula

For n>2: a(n) = A000040(n) + 2 + A010051(A000040(n) + 2) + 1. - Reinhard Zumkeller, Mar 29 2010 [corrected by Georg Fischer, Oct 06 2024]

Extensions

More terms from Reinhard Zumkeller, Mar 29 2010

a(49), a(52) and a(57) corrected by Georg Fischer, Oct 06 2024