A075749 Numbers k such that 210*k +- 1 are twin primes.

2, 5, 11, 13, 16, 28, 29, 30, 35, 36, 42, 44, 50, 51, 55, 57, 73, 86, 104, 121, 125, 128, 135, 140, 147, 148, 157, 158, 160, 161, 165, 168, 179, 193, 204, 205, 209, 223, 244, 247, 249, 251, 255, 264, 271, 273, 277, 281, 282, 290, 302, 304, 310, 312, 313, 316

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

k = 2 is a term since 210*2 - 1 = 419 and 210*2 + 1 = 421 are twin primes.

Mathematica

Select[Range[6! ], PrimeQ[210*#-1]&&PrimeQ[210*#+1]&] (* Vladimir Joseph Stephan Orlovsky, Apr 08 2010 *)

Prog

(PARI) isok(n) = isprime(210*n+1) && isprime(210*n-1); \\ Michel Marcus, Jan 14 2015
(Magma) [k:k in [1..320]| IsPrime(210*k-1) and IsPrime(210*k+1)]; // Marius A. Burtea, Jan 01 2020

Crossrefs

Cf. A002822 (with 6*k +- 1), A176114 (with 30*k +- 1).

Sequence in context: A032541 A363981 A281644 * A138837 A038899 A218582

Adjacent sequences: A075746 A075747 A075748 * A075750 A075751 A075752

Keyword

easy,nonn

Author

Zak Seidov, Oct 08 2002

Status

approved