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 A063378 Smallest number whose Sophie Germain degree (see A063377) is n. 1
 4, 7, 3, 11, 5, 2, 89, 1122659, 19099919, 85864769, 26089808579, 665043081119, 554688278429, 4090932431513069, 95405042230542329 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Also known as Cunningham chains of length n of the first kind. For each positive integer n, is there some integer with Sophie Germain degree of n? LINKS Warut Roonguthai, Yves Gallot's Proth.exe and Cunningham Chains EXAMPLE Using f(x)=2x+1, 11 -> 23 -> 47 -> 95, which is composite; thus a(3)=11. MATHEMATICA 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}] CROSSREFS Cf. A005384, A063377. Sequence in context: A100127 A130204 A021215 * A280547 A201412 A272056 Adjacent sequences:  A063375 A063376 A063377 * A063379 A063380 A063381 KEYWORD hard,more,nonn AUTHOR Reiner Martin (reinermartin(AT)hotmail.com), Jul 14 2001 EXTENSIONS More terms from Jud McCranie, Jul 20 2001 Edited and extended by Robert G. Wilson v, Nov 21 2002 STATUS approved

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Last modified May 30 08:46 EDT 2017. Contains 287302 sequences.