login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

a(n) is the smallest "lesser twin" prime p, such that prime(2 + p) - prime(p) = 2n (cf. A096474).
1

%I #20 Jul 28 2017 16:45:44

%S 3,17,11,41,71,101,29,569,881,137,1151,521,1289,2027,10331,1229,3461,

%T 461,2549,2129,6569,6131,14387,34157,5657,4259,44621,17387,25301,

%U 11159,56099,34367,64877,23201,80147,73361,21017,46349,162287,94439,469877,122501,35507

%N a(n) is the smallest "lesser twin" prime p, such that prime(2 + p) - prime(p) = 2n (cf. A096474).

%F a(n) = min{x; A096474(x) = 2n} for n = 3, 4, ...

%t {ta = Table[0, {1300}], tb = Table[0, {1300}], tc = Table[0, {1300}], u = 1}; Do[s = Prime[n + 1] - Prime[n]; If[s == 2, ta[[u]] = Prime[Prime[n + 1]] - Prime[Prime[n]]; tb[[u]] = n; tc[[u]] = Prime[n]; u = u + 1], {n, 1, 10000}]; a[n_] := tc[[FirstPosition[ta, 2 n][[1]]]]; Table[a[n], {n, 3, 40}] (* _Jean-François Alcover_, Jul 28 2017, using Mathematica code for A096464 *)

%o (PARI) a(n) = {forprime(p=3, , if (isprime(p+2) && (prime(2+p)-prime(p) == 2*n), return (p))); p=3;} \\ _Michel Marcus_, Jul 28 2017

%Y Cf. A001359, A096474, A096476.

%K nonn

%O 3,1

%A _Labos Elemer_, Jun 23 2004

%E Name edited by _Michel Marcus_, Jul 28 2017

%E a(41)-a(45) from _Michel Marcus_, Jul 28 2017