A216075 Numbers n such that 2*prime(n) - prime(n+1) is prime.

3, 4, 9, 15, 16, 21, 37, 40, 47, 51, 55, 56, 71, 74, 103, 108, 111, 114, 118, 119, 130, 161, 165, 180, 184, 185, 188, 195, 200, 208, 219, 227, 231, 232, 238, 239, 240, 255, 267, 272, 273, 274, 278, 290, 292, 317, 326, 340, 354, 359, 381, 388, 392, 396, 416

Offset

1,1

Comments

Corresponding values of 2*prime(n) - prime(n+1) are in A215808.

Links

Zak Seidov, Table of n, a(n) for n = 1..1000

Mathematica

f[n_]:=(2Prime[n]-Prime[n+1]); Select[Range[1000], PrimeQ[f[#]]&]
Position[Partition[Prime[Range[500]], 2, 1], _?(PrimeQ[2#[[1]]-#[[2]]]&), 1, Heads->False]//Flatten (* Harvey P. Dale, Apr 06 2018 *)

Prog

(PARI) list(lim)=my(v=List(), n, p=2); forprime(q=3, , if(n++>lim, return(Vec(v))); if(isprime(2*p-q), listput(v, n)); p=q) \\ Charles R Greathouse IV, May 22 2017

Crossrefs

Cf. A215808.

Sequence in context: A321680 A215667 A125874 * A253197 A255064 A369116

Adjacent sequences: A216072 A216073 A216074 * A216076 A216077 A216078

Keyword

nonn

Author

Zak Seidov, Sep 06 2012

Status

approved