A174258 Numbers n such that exactly one of 3*prime(n)-4 and 3*prime(n)+4 is prime.

1, 4, 6, 7, 9, 10, 12, 13, 15, 16, 18, 19, 21, 26, 27, 28, 29, 34, 35, 37, 40, 41, 42, 45, 48, 49, 54, 57, 58, 59, 60, 61, 62, 66, 67, 70, 71, 73, 74, 76, 78, 82, 84, 85, 88, 92, 95, 101, 102, 103, 105, 108, 109, 113, 114, 115, 117, 120, 123, 124, 125, 126, 127, 130, 134

Offset

1,2

Links

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

Example

a(1)=1 because 3*prime(1)-4=2 is prime and 3*prime(1)+4=10 is composite; a(2)=4 because 3*prime(4)-4=17 is prime and 3*prime(4)+4=25 is composite.

Mathematica

Select[Range[200], Total[Boole[PrimeQ[3Prime[#]+{4, -4}]]]==1&] (* Harvey P. Dale, May 08 2019 *)

Crossrefs

Sequence in context: A179242 A104425 A345447 * A080746 A246362 A069909

Adjacent sequences: A174255 A174256 A174257 * A174259 A174260 A174261

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Mar 14 2010

Extensions

Corrected by Charles R Greathouse IV, Mar 19 2010

Status

approved