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A216075 Numbers n such that 2*prime(n) - prime(n+1) is prime. 3
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 (list; graph; refs; listen; history; text; internal format)
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 A165921

Adjacent sequences:  A216072 A216073 A216074 * A216076 A216077 A216078

KEYWORD

nonn

AUTHOR

Zak Seidov, Sep 06 2012

STATUS

approved

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Last modified September 17 07:51 EDT 2021. Contains 347478 sequences. (Running on oeis4.)