OFFSET
1,3
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..1500
EXAMPLE
MAPLE
f:= n -> nops(select(k -> isprime(2^n-2^k-1), [$1..n-1])):
map(f, [$1..100]); # Robert Israel, Jun 12 2018
MATHEMATICA
a[n_] := Module[{m = 2^n - 1, cnt = 0}, For[ k = 1, k < n, k++, If[PrimeQ[m - 2^k], cnt++]]; cnt]; Table[a[n], {n, 2, 86}] (* Jean-François Alcover, Sep 12 2013 *)
PROG
(Haskell)
a208083 = sum . map a010051 . a081118_row
(PARI) a(n)=sum(k=1, n-1, ispseudoprime(2^n-2^k-1)) \\ Charles R Greathouse IV, Sep 12 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 23 2012
STATUS
approved