%I #15 Jul 06 2018 17:11:05

%S 1,2,2,2,4,2,2,4,2,2,4,2,4,6,2,2,4,6,2,4,2,2,4,2,4,6,2,4,6,2,2,4,6,2,

%T 4,2,2,4,6,2,4,2,4,6,2,4,6,8,2,4,2,2,4,2,2,4,2,4,6,8,10,12,14,2,4,2,4,

%U 6,2,2,4,6,8,10,2,2,4,6,2,4,6,2,4,2,4,6,2,4,6,2,2,4

%N a(n) = 2*n + 1 - prevprime(2*n + 1).

%H Robert Israel, <a href="/A049716/b049716.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A049711(2*n+1). - _R. J. Mathar_, Oct 26 2015

%e n: 1 2 3 4 5 6 7 8 ...

%e 2n+1: 3 5 7 9 11 13 15 17 ...

%e pp: 2 3 5 7 7 11 13 13 ...

%e diff: 1 2 2 2 4 2 2 4 ...

%p seq(2*n+1-prevprime(2*n+1), n=1..100); # _Robert Israel_, Jul 05 2018

%t Table[2n+1-NextPrime[2n+1,-1],{n,100}] (* _Harvey P. Dale_, Sep 21 2013 *)

%o (PARI) a(n) = 2*n+1-precprime(2*n); \\ _Michel Marcus_, Jul 06 2018

%Y Cf. A049613, A049653, A049711, A049847.

%K nonn

%O 1,2

%A _N. J. A. Sloane_