A238327 Recursively defined by a(0) = 1, a(n + 1) = p + 2, where p is the least prime greater than a(n).

1, 4, 7, 13, 19, 25, 31, 39, 43, 49, 55, 61, 69, 73, 81, 85, 91, 99, 103, 109, 115, 129, 133, 139, 151, 159, 165, 169, 175, 181, 193, 199, 213, 225, 229, 235, 241, 253, 259, 265, 271, 279, 283, 295, 309, 313, 319, 333, 339, 349, 355, 361, 369, 375, 381, 385, 391, 399, 403

Offset

0,2

Comments

When a(n) is prime, it is the second member of a twin prime pair. Moreover, every twin prime pair except 3,5 is found in this manner.

All members between 7 and 333 are also in A076974. - Ralf Stephan, Feb 28 2014

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Formula

a(n+1) = A151800(a(n)) + 2. - Reinhard Zumkeller, Feb 28 2014

Mathematica

a[0] := 1; a[n_] := a[n] = Prime[PrimePi[a[n - 1]] + 1] + 2; Table[a[n], {n, 0, 59}] (* Alonso del Arte, Feb 24 2014 *)

Prog

(Haskell)
a238327 n = a238327_list !! n
a238327_list = iterate ((+ 2) . a151800) 1
-- Reinhard Zumkeller, Feb 28 2014

Crossrefs

Sequence in context: A111710 A191138 A075315 * A243811 A194073 A023496

Adjacent sequences: A238324 A238325 A238326 * A238328 A238329 A238330

Keyword

nonn

Author

Curtis Herink, Feb 24 2014

Status

approved