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A196446 Numbers n such that both n and (n-1)^2*2^n-1 are primes. 1
2, 3, 19, 29, 43, 61, 79, 109, 151, 167, 2311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes p such that (p-1)^2*2^p-1 is also prime.

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

a(1)=2 because 2 is a prime and (2-1)^2*2^2-1=3 is a prime,

a(2)=3 because 3 is a prime and (3-1)^2*2^3-1=31 is a prime,

a(3)=19 because 19 is a prime and (19-1)^2*2^19-1=169869313 is a prime,

a(4)=29 because 29 is a prime and (29-1)^2*2^29-1=420906795007 is a prime.

MATHEMATICA

Select[Prime[Range[40]], PrimeQ[(#-1)^2 2^#-1]&] (* The program generates the first 10 terms *) (* Harvey P. Dale, Sep 06 2017 *)

CROSSREFS

Sequence in context: A215383 A215387 A140555 * A265799 A058912 A040145

Adjacent sequences:  A196443 A196444 A196445 * A196447 A196448 A196449

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Oct 02 2011

STATUS

approved

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Last modified November 24 07:53 EST 2020. Contains 338607 sequences. (Running on oeis4.)