A104296 a(n) = prime((a(n)-1)/2), a(1)=9.

9, 11, 13, 17, 23, 37, 67, 139, 349, 1039, 3727, 16007, 81853, 492059, 3436987, 27605857, 252391267, 2602897093, 30034790941, 384953881369, 5444681375227, 84482367674813

Offset

1,1

Comments

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.

Links

Table of n, a(n) for n=1..22.

Mathematica

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 *)

Crossrefs

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

Sequence in context: A120177 A291350 A289697 * A254936 A117675 A027726

Adjacent sequences: A104293 A104294 A104295 * A104297 A104298 A104299

Keyword

easy,nonn

Author

Zak Seidov, Feb 28 2005

Extensions

a(14) - a(22) from Robert G. Wilson v, Mar 24 2005

Status

approved