A172147 Numbers n such that 42n - 5 and 42n + 5 are prime.

1, 2, 4, 9, 11, 12, 17, 18, 21, 22, 26, 28, 29, 31, 34, 37, 43, 49, 56, 57, 64, 66, 68, 79, 86, 88, 104, 106, 114, 117, 119, 121, 133, 138, 144, 148, 152, 166, 171, 172, 182, 183, 192, 193, 199, 204, 207, 208, 213, 218, 224, 229, 232, 233, 242, 244, 249, 257, 264, 268, 276

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Example

a(1)=1 because 42*1 - 5 = 37 and 42*1 + 5 = 47 are both prime.

Mathematica

Select[Range[280], PrimeQ[42 # - 5] && PrimeQ[42 # + 5] &] (* Ivan Neretin, Jan 24 2017 *)

Crossrefs

Sequence in context: A096692 A203847 A365811 * A266726 A030194 A190494

Adjacent sequences: A172144 A172145 A172146 * A172148 A172149 A172150

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Jan 26 2010

Extensions

Corrected by Charles R Greathouse IV, Mar 19 2010

Status

approved