A171836 Primes of the form 6n+1 with prime index of the form 6n+1.

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

1,1

Comments

This is to primes of form 6n+1 (A002476) as primes with prime subscripts (A006450) is to primes (A000040). Hence this is one of four related sequences into which every prime with prime subscripts (A006450) may be classified: Primes of the form 6n+1 (A002476) with prime index of the form 6n+1; primes of the form 6n+1 with prime index of form 6n-1 (A007528); primes of the form 6n-1 with prime index of the form 6n+1; and primes of form 6n-1 with prime index of the form 6n-1.

Links

Table of n, a(n) for n=1..44.

Formula

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

Example

a(1) = 61 because the smallest prime of form 6n+1 is 6*1+1 = 7, and the seventh prime of the form 6n+1 is 6*10+1 = 61. a(2) = 109 because the second smallest prime of form 6n+1 is 6*2+1 = 13, and the thirteenth prime of the form 6n+1 is 6*18+1 = 109.

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

Crossrefs

Cf. A000040, A002476, A006450, A007528, A171833.

Sequence in context: A107152 A141301 A139898 * A140009 A197719 A140372

Adjacent sequences: A171833 A171834 A171835 * A171837 A171838 A171839

Keyword

easy,nonn

Author

Jonathan Vos Post, Dec 19 2009

Extensions

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

Status

approved