

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
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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

Table of n, a(n) for n=0..14.
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 * A201412 A020803 A019626
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



