A160594 - OEIS

%I #12 Mar 02 2021 03:19:45

%S 6,12,18,21,25,29,37,42,44,50,53,59,65,68,70,74,78,80,82,84,88,100,

%T 106,110,112,121,122,127,130,134,136,145,147,151,159,168,169,172,174,

%U 180,183,187,189,191,197,198,203,204,211,216,221,226,231,237,244,251,254

%N Indices of primes congruent to 1 modulo 12.

%C The asymptotic density of this sequence is 1/4 (by Dirichlet's theorem). - _Amiram Eldar_, Mar 02 2021

%H Harvey P. Dale, <a href="/A160594/b160594.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000720(A068228(n)).

%e a(1) = 6 since the 6th prime, A000040(6) = 13, is the first one to be equal to 1 (mod 12).

%e a(2) = 12 since the 12th prime, A000040(12) = 37, is the second one to be equal to 1 (mod 12).

%t PrimePi/@Select[Range[1,1701,12],PrimeQ] (* _Harvey P. Dale_, Nov 28 2011 *)

%o (PARI) for( n=1,999, prime(n)%12==1 & print1(n","))

%Y A116614 lists the even terms of this sequence, divided by 2.

%Y Cf. A000720, A068228.

%K nonn

%O 1,1

%A _M. F. Hasler_, May 22 2009