Search: id:A063378
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%I A063378
%S A063378 4,7,3,11,5,2,89,1122659,19099919,85864769,26089808579,665043081119,
%T A063378 554688278429,4090932431513069,95405042230542329
%N A063378 Smallest number whose Sophie Germain degree (see A063377) is n.
%C A063378 Also known as Cunningham chains of length n of the first kind.
%C A063378 For each positive integer n, is there some integer with Sophie Germain 
               degree of n?
%H A063378 Warut Roonguthai, <a href="http://ksc9.th.com/warut/cunningham.html">
               Yves Gallot's Proth.exe and Cunningham Chains</a>
%e A063378 Using f(x)=2x+1, 11 -> 23 -> 47 -> 95, which is composite; thus a(3)=11.
%t A063378 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 A063378 Cf. A005384, A063377.
%Y A063378 Sequence in context: A100127 A130204 A021215 this_sequence A020803 A019626 
               A005472
%Y A063378 Adjacent sequences: A063375 A063376 A063377 this_sequence A063379 A063380 
               A063381
%K A063378 hard,more,nonn
%O A063378 0,1
%A A063378 Reiner Martin (reinermartin(AT)hotmail.com), Jul 14 2001
%E A063378 More terms from Jud McCranie (j.mccranie(AT)comcast.net), Jul 20 2001
%E A063378 Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 21 
               2002

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