A171836 a(n) = A002476(A002476(n)).

61, 109, 181, 331, 397, 463, 727, 787, 877, 991, 1231, 1303, 1429, 1669, 1831, 2029, 2137, 2239, 2539, 2713, 2797, 3049, 3253, 3319, 3517, 3967, 4093, 4177, 4603, 4723, 5011, 5113, 5413, 5659, 5749, 5851, 6211, 6379, 6607, 6793, 6907, 7297, 7393, 7789

Offset: 1

Author

Jonathan Vos Post, Dec 19 2009

Keywords

• easy
• nonn

Comments

a(n) is the p-th prime == 1 (mod 6), where p is the n-th prime == 1 (mod 6). - Robert Israel, Nov 22 2024

Examples

			a(3) = 181 because A002476(3) = 19 is the third prime == 1 (mod 6), and A002476(19) = 181 is the 19th prime == 1 (mod 6). - _Robert Israel_, Nov 22 2024
		

Links

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

Crossrefs

Cf. A002476.

Programs

Maple

A002476 := proc(n) if n= 1 then 7; else a := nextprime( procname(n-1)) ; while true do if a mod 6 = 1 then return a; end if; a := nextprime(a) ; end do ; end if; end proc: A171836 := proc(n) A002476(A002476(n)) ; end proc: seq(A171836(n),n=1..80) ; # R. J. Mathar, Jan 25 2010

Mathematica

With[{pr=Select[6*Range[2000]+1,PrimeQ]},Table[pr[[pr[[i]]]],{i,50}]] (* Harvey P. Dale, Dec 22 2013 *)

Formula

a(n) = A002476(A002476(n)).

Extensions

More terms from R. J. Mathar, Jan 25 2010