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A099440
Primes of the form A000295(k) = 2^k - k - 1.
5
11, 1013, 16369, 65519, 67108837, 1125899906842573, 72057594037927879, 1180591620717411303353, 83076749736557242056487941267521419
OFFSET
1,1
COMMENTS
The next term a(10) = 2^2072-2073 has 624 decimal digits.
a(11) has 1882 decimal digits. - Vincenzo Librandi, Jul 18 2012
LINKS
EXAMPLE
a(2) = 1013 because A000295(A099439(2)) = 2^10 - 10 - 1 is prime.
MATHEMATICA
Select[Table[2^n-n-1, {n, 0, 7000}], PrimeQ] (* Vincenzo Librandi, Jul 18 2012 *)
PROG
(Magma) [ a: n in [1..200] | IsPrime(a) where a is 2^n-n-1 ]; // Vincenzo Librandi, Jul 18 2012
CROSSREFS
Cf. A000295 2^n-n-1 (column 2 of the Eulerian numbers), A099439 2^n-n-1 is prime, A099441 2^n-n-1 is a semiprime, A099442 semiprimes in A000295.
Sequence in context: A303786 A015511 A065050 * A073903 A069710 A046187
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Oct 18 2004
STATUS
approved