A176820 - OEIS

%I #7 Oct 14 2024 00:11:09

%S 1,2,1,1,1,1,2,0,1,0,0,1,1,1,1,1,1,2,0,1,0,1,1,0,1,1,1,0,0,1,0,1,0,0,

%T 1,1,0,0,1,0,1,1,1,0,1,0,1,1,1,1,0,1,1,0,1,0,0,0,0,2,0,0,1,1,1,1,1,0,

%U 1,0,1,0,1,0,0,0,0,1,1,0,0,2,0,0,0,0,1,0,1,0,1,0,0,0,0,0,0,0,0,1,0,0,1,1,0

%N Number of primes between 3*A171821(2n-1) and 3*A171821(2n).

%C Where 2 together with twin primes in A171821.

%e a(1)=1 because 7 is between 3*A171821(2*1-1)=6 and 3*A171821(2*1)=9.

%e a(2)=2 because 17 and 19 are between 3*A171821(2*2-1)=15 and 3*A171821(2*2)=21.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Apr 26 2010

%E a(42) corrected by _R. J. Mathar_, May 06 2010