|
%I #30 May 17 2023 08:35:03
%S 2,4,8,12,16,40,80,314,478,604,634,790,868,1264,1376,2536,3544,6564,
%T 7268,7780,8366,15010,16636,18672,27084,29954,51968,60940
%N Numbers k such that k*2^k - k - 1 is prime.
%C The corresponding primes are given in A046842.
%C a(27) > 50000. - _Tyler NeSmith_, Apr 16 2022
%p A046843:=n->`if`(isprime(n*2^n-n-1), n, NULL): seq(A046843(n), n=1..1000); # _Wesley Ivan Hurt_, Oct 12 2014
%t Select[Range[10000],PrimeQ[# 2^#-#-1]&] (* _Harvey P. Dale_, Oct 10 2011 *)
%o (PARI) is(n)=ispseudoprime(n*2^n-n-1) \\ _Charles R Greathouse IV_, May 22 2017
%Y Cf. A046842.
%K nonn,more
%O 1,1
%A _Felice Russo_
%E Sign in definition corrected by _R. J. Mathar_, Oct 10 2010
%E a(10)-a(21) from _Harvey P. Dale_, Oct 10 2011
%E a(22)-a(26) from _Tyler NeSmith_, Apr 16 2022
%E a(27)-a(28) from _Michael S. Branicky_, May 17 2023
|
