The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #7 Oct 30 2022 18:19:59
%S 4,7,3,11,5,2,89,1122659,19099919,85864769,26089808579,665043081119,
%T 554688278429,4090932431513069,95405042230542329
%N Smallest number whose Sophie Germain degree (see A063377) is n.
%C Also known as Cunningham chains of length n of the first kind.
%C For each positive integer n, is there some integer with Sophie Germain degree of n?
%H Warut Roonguthai, <a href="http://ksc9.th.com/warut/cunningham.html">Yves Gallot's Proth.exe and Cunningham Chains</a>
%e Using f(x)=2x+1, 11 -> 23 -> 47 -> 95, which is composite; thus a(3)=11.
%t NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; f[n_] := Block[{k = 2}, While[ Length[ NestWhileList[2# + 1 &, k, PrimeQ]] != n + 1, k = NextPrim[k]]; k]; Table[f[n], {n, 1, 8}]
%Y Cf. A005384, A063377.
%K hard,more,nonn
%O 0,1
%A _Reiner Martin_, Jul 14 2001
%E More terms from _Jud McCranie_, Jul 20 2001
%E Edited and extended by _Robert G. Wilson v_, Nov 21 2002