A104296 - OEIS

%I #7 Mar 29 2015 14:23:19

%S 9,11,13,17,23,37,67,139,349,1039,3727,16007,81853,492059,3436987,

%T 27605857,252391267,2602897093,30034790941,384953881369,5444681375227,

%U 84482367674813

%N a(n) = prime((a(n)-1)/2), a(1)=9.

%C All primes except a(1) which is any odd integer; a(1)=9 is first a(1) giving nontrivial sequence: three cases a(1)=3,5,7 give a(n)=a(1); other a(1)'s A104297-A104304.

%t a[1] = 9; a[n_] := a[n] = Prime[(a[n - 1] + 1)/2]; Table[ a[n], {n, 22}] (* _Robert G. Wilson v_, Mar 24 2005 *)

%Y Cf. A104297, A104298, A104299, A104300, A104301, A104302, A104303, A104304.

%K easy,nonn

%O 1,1

%A _Zak Seidov_, Feb 28 2005

%E a(14) - a(22) from _Robert G. Wilson v_, Mar 24 2005