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A005850 Primes p such that the NSW number A002315((p-1)/2) is prime.
(Formerly M2426)
2
3, 5, 7, 19, 29, 47, 59, 163, 257, 421, 937, 947, 1493, 1901, 6689, 8087, 9679, 28753, 79043, 129127, 145969, 165799, 168677, 170413, 172243 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Some of the larger entries may only correspond to probable primes.
REFERENCES
P. Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 290.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
M. Newman, D. Shanks, H. Williams, Simple groups of square order and interesting sequence of primes, Acta Arithmetica (1980), Volume: 38, Issue: 2, page 129-140
Eric Weisstein's World of Mathematics, Pell Number
Eric Weisstein's World of Mathematics, Pythagoras's Constant
FORMULA
A088165(n) mod a(n) = 1. - Altug Alkan, Mar 17 2016
MATHEMATICA
max = 10000 (* computation is very slow beyond this limit *); nc = Numerator[Convergents[Sqrt[2], max]]; Reap[Do[If[PrimeQ[n], If[PrimeQ[nc[[n]]], Print[n]; Sow[n]]] , {n, 3, max}]][[2, 1]] (* Jean-François Alcover, Oct 22 2012, after David Applegate *)
PROG
(PARI) is(n)=my(w=3+quadgen(32)); isprime(n) && n>2 && ispseudoprime(imag((1+w)*w^(n\2))) \\ Charles R Greathouse IV, Oct 19 2012
CROSSREFS
A099088 is a closely related sequence.
Sequence in context: A079131 A179687 A106919 * A052334 A322302 A154526
KEYWORD
nonn,nice,hard
AUTHOR
EXTENSIONS
6689, 8087, 9679 reported by Warut Roonguthai on the PrimeForm mailing list.
28753 found by Andrew Walker (ajw01(AT)uow.edu.au), Jul 12 2001.
129127, 145969, 165799, 168677, 170413, 172243 found by Eric W. Weisstein, May 22 2006 - Jan 25 2007 [from Mike Oakes, Mar 29 2009]
STATUS
approved

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Last modified March 19 04:26 EDT 2024. Contains 370952 sequences. (Running on oeis4.)