%I #10 Sep 08 2022 08:45:11

%S 3,3,1,3,3,1,3,2,1,3,1,1,2,3,1,1,3,1,3,3,1,2,1,1,3,1,1,2,2,1,1,3,1,3,

%T 2,1,1,2,1,3,1,1,2,1,1,1,3,1,3,2,1,3,2,1,3,1,1,1,1,1,1,3,1,2,1,1,3,2,

%U 1,1,1,1,2,2,1,1,3,1,1,2,1,3,1,1,2,1,1,2,3,1,1,1,1,3,3,1,2,2,1,1

%N Number of primes in arithmetic progression starting with 3 and with d = 2n.

%C The arithmetic progression is stopped when the next term is not prime. E.g., for n=5, a=3, the numbers 3, 13, and 23 are prime, while the next term, 33, is not prime.

%C a(n) <= 3 because 3+3*d is divisible by 3. - _Klaus Brockhaus_, May 14 2009

%o (Magma) npap3:=function(d) c:=1; p:=3+d; while IsPrime(p) do c+:=1; p+:=d; end while; return c; end function; [ npap3(2*n): n in [1..105] ]; // _Klaus Brockhaus_, May 14 2009

%Y Cf. A088421, A088422, A088423, A088424, A088425, A088426, A088427, A088428, A088429.

%Y Cf. A115334. - _Klaus Brockhaus_, May 14 2009

%K easy,nonn

%O 1,1

%A _Zak Seidov_, Sep 29 2003