A175122 a(1)=3. a(n) = smallest prime > a(n-1) such that a(n)-a(n-1) = 2*m, where m is composite.

3, 11, 19, 31, 43, 59, 67, 79, 97, 109, 127, 139, 151, 163, 179, 191, 199, 211, 223, 239, 251, 263, 271, 283, 307, 331, 347, 359, 367, 379, 397, 409, 421, 433, 449, 457, 487, 499, 523, 541, 557, 569, 577, 593, 601, 613, 631, 643, 659, 677, 701, 709, 727, 739

Offset

1,1

Comments

A175123(n)*2 = a(n+1) - a(n).

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

spn[n_]:=Module[{k=NextPrime[n]}, While[!CompositeQ[(k-n)/2], k= NextPrime[ k]]; k]; NestList[spn, 3, 60] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 30 2019 *)

Crossrefs

Cf. A175123.

Sequence in context: A125994 A137295 A038536 * A031369 A014223 A023265

Adjacent sequences: A175119 A175120 A175121 * A175123 A175124 A175125

Keyword

nonn

Author

Leroy Quet, Feb 15 2010

Extensions

Extended by Ray Chandler, Mar 06 2010

Status

approved