%I #5 Oct 12 2013 15:24:51

%S 2,3,4,5,8,9,17,32,128,257,8192,65537,131072,524288,2147483648,

%T 2305843009213693952,618970019642690137449562112,

%U 162259276829213363391578010288128

%N Greater of prime powers that differ by 1. In other words, numbers n such that n-1 and n are prime powers.

%C See comments in A006549.

%F a(n) = A006549(n) + 1. - _Michel Marcus_, Aug 25 2013

%o (PARI) isokp(n) = (n==1) || isprime(n) || (ispower(n, ,&k) && isprime(k));

%o isok(n) = isokp(n) && isokp(n-1); \\ _Michel Marcus_, Aug 25 2013

%Y Cf. A006549.

%K nonn

%O 1,1

%A _Greg Huber_, Jul 13 2006