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A046843 Numbers n such that n*2^n-n-1 is prime. 2
2, 4, 8, 12, 16, 40, 80, 314, 478, 604, 634, 790, 868, 1264, 1376, 2536, 3544, 6564, 7268, 7780, 8366 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The corresponding primes are given in A046842.

LINKS

Table of n, a(n) for n=1..21.

MAPLE

A046843:=n->`if`(isprime(n*2^n-n-1), n, NULL): seq(A046843(n), n=1..1000); # Wesley Ivan Hurt, Oct 12 2014

MATHEMATICA

Select[Range[10000], PrimeQ[# 2^#-#-1]&] (* Harvey P. Dale, Oct 10 2011 *)

PROG

(PARI) is(n)=ispseudoprime(n*2^n-n-1) \\ Charles R Greathouse IV, May 22 2017

CROSSREFS

Cf. A046842.

Sequence in context: A152768 A266047 A273109 * A292060 A152125 A176562

Adjacent sequences:  A046840 A046841 A046842 * A046844 A046845 A046846

KEYWORD

nonn,more

AUTHOR

Felice Russo

EXTENSIONS

Sign in definition corrected by R. J. Mathar, Oct 10 2010

More terms from Harvey P. Dale, Oct 10 2011

STATUS

approved

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Last modified February 21 07:18 EST 2018. Contains 299390 sequences. (Running on oeis4.)