A189118 a(n) = smallest composite (odd) number greater than a(n-1) such that a(n)+2n is the first prime after a(n).

9, 25, 91, 119, 201, 295, 527, 891, 1133, 1341, 1671, 2479, 2973, 4299, 5593, 8469, 9553, 15691, 16145, 19621, 25481, 28233, 31423, 31909, 34073, 35619, 43337, 44295, 89695, 107381, 134519, 155943, 173363, 175143, 188037, 212705, 265629

Offset

1,1

Comments

More precise definition from Don Reble, Jul 29 2014. (Old definition was: Smallest composite odd number of first sequence of n consecutive composite odd numbers.)

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..70

Example

9 is composite but 11 is not; 25 and 27 are composite but 29 is not; 91, 93, 95 are composite but 97 is not.

Mathematica

imax=1000000; lst={}; q=1; Do[k=0; Do[If[PrimeQ[n], Break[], k++], {n, m, imax+200, 2}]; If[k==q, q++; AppendTo[lst, m]], {m, 5, imax, 2}]; lst

Crossrefs

Cf. A002808, A071904, A161945, A075067.

Sequence in context: A269662 A147428 A147436 * A075067 A075064 A147332

Adjacent sequences: A189115 A189116 A189117 * A189119 A189120 A189121

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Apr 16 2011

Extensions

Definition revised by N. J. A. Sloane, Jul 29 2014 at the suggestion of Don Reble.

Status

approved