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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
OFFSET
1,1
COMMENTS
Corresponding values of 2*prime(n) - prime(n+1) are in A215808.
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
KEYWORD
nonn
AUTHOR
Zak Seidov, Sep 06 2012
STATUS
approved