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A063378
Smallest number whose Sophie Germain degree (see A063377) is n.
4
4, 7, 3, 11, 5, 2, 89, 1122659, 19099919, 85864769, 26089808579, 665043081119, 554688278429, 4090932431513069, 95405042230542329
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?
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
Sequence in context: A100127 A130204 A021215 * A280547 A301930 A365940
KEYWORD
hard,more,nonn
AUTHOR
Reiner Martin, 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