A172056 - OEIS

A172056

Primes p such that 2*p+-1 and 2*p+-3 are all composites.

59, 61, 103, 109, 149, 151, 163, 257, 313, 389, 401, 449, 479, 541, 569, 571, 673, 677, 709, 733, 769, 821, 823, 839, 857, 883, 919, 947, 971, 983, 1061, 1087, 1093, 1097, 1129, 1151, 1163, 1181, 1249, 1283, 1301, 1319, 1321, 1381, 1433, 1489, 1493, 1549

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OFFSET

1,1

LINKS

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

EXAMPLE

a(1)=59 because 2*59-1=117, 2*59+1=119, 2*59-3=115, 2*59+3=121 are all composites.

MATHEMATICA

okQ[n_]:=Union[PrimeQ[{2n+1, 2n-1, 2n+3, 2n-3}]]=={False}; Select[Prime[Range[250]], okQ] (* Harvey P. Dale, Feb 07 2010 *)

Select[Prime[Range[300]], AllTrue[2#+{1, 3, -1, -3}, CompositeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 20 2015 *)

CROSSREFS

Cf. A000040, A002808, A068497.

Sequence in context: A042739 A348570 A172256 * A032648 A235808 A290170

Adjacent sequences: A172053 A172054 A172055 * A172057 A172058 A172059

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jan 24 2010

EXTENSIONS

Corrected and extended by Harvey P. Dale, Feb 07 2010

STATUS

approved