A104297 - OEIS

%I #9 Mar 29 2015 13:18:58

%S 21,31,53,103,239,659,2213,8887,42473,240151,1584607,12069311,

%T 105036509,1034651039,11438277847,142253144233,1946420671121,

%U 29165259660989

%N a(n) = prime((a(n-1) + 1)/2), a(1)=21.

%C All primes except a(1) which is any odd integer; a(1)=21 the least integer missing in A104296 and A104298.

%t a[1] = 21; a[n_] := a[n] = Prime[(a[n - 1] + 1)/2]; Table[ a[n], {n, 18}] (* _Robert G. Wilson v_, Mar 24 2005 *)

%Y Cf. A104296, A104298, A104299, A104300, A104301, A104302, A104303, A104304.

%K easy,nonn

%O 1,1

%A _Zak Seidov_, Mar 20 2005

%E a(14)-a(18) from _Robert G. Wilson v_, Mar 24 2005