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A075749 Numbers k such that 210*k +- 1 are twin primes. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A065433 A032541 A281644 * A138837 A038899 A218582

Adjacent sequences:  A075746 A075747 A075748 * A075750 A075751 A075752

KEYWORD

easy,nonn

AUTHOR

Zak Seidov, Oct 08 2002

STATUS

approved

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Last modified August 12 17:17 EDT 2020. Contains 336439 sequences. (Running on oeis4.)