OFFSET
1,1
COMMENTS
If p = 2^n-5 is prime, then p*2^(n-1) is abundant with abundance 4 (see A088832). - Davide Rotondo, Oct 25 2020
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..28
FORMULA
a(n) = 2^A059608(n) - 5.
MATHEMATICA
Select[Table[2^n-5, {n, 2, 400}], PrimeQ] (* Vincenzo Librandi, Jul 26 2012 *)
PROG
(Magma) [ a: n in [2..500] | IsPrime(a) where a is 2^n-5 ];
(PARI) for(n=1, 300, q=2^n-5; if(isprime(q), print(q))) /* gives more terms in <10secs */ \\ Joerg Arndt, Dec 03 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Feb 10 2009
EXTENSIONS
Edited by Zak Seidov
STATUS
approved