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A157358 Triple-safe primes p. 4
23, 47, 719, 1439, 2879, 4079, 9839, 11279, 21599, 28319, 51599, 84719, 92399, 95279, 96959, 137279, 157679, 159119, 178799, 209519, 219839, 243119, 349199, 429119, 430799, 441839, 462719, 481199, 491279, 507359, 533999, 571199, 597599 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These occur in a proof of nonexistence of a certain type of permutation group for p (Theorem 8 by Ito). - R. J. Mathar, May 29 2011

LINKS

Table of n, a(n) for n=1..33.

Noboru Ito, Transitive permutation groups of degree p=2q+1, p and q being prime numbers, Bull. AMS 69 (2) (1963), 165-192.

EXAMPLE

(23-1)/2=11, (11-1)/2=5, (5-1)/2=2(prime), ...

MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[a=(p-1)/2]&&PrimeQ[b=(a-1)/2]&&PrimeQ[(b-1)/2], AppendTo[lst, p]], {n, 9!}]; lst

CROSSREFS

Cf. A005385, A066179, A157357.

Sequence in context: A042054 A084667 A255596 * A158238 A328799 A333115

Adjacent sequences:  A157355 A157356 A157357 * A157359 A157360 A157361

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 27 2009

STATUS

approved

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Last modified July 15 00:36 EDT 2020. Contains 335762 sequences. (Running on oeis4.)