A138303 Numbers n such that n*(n+1)-1 and n*(n+1)+1 are twin primes and n*(n+3)-1 and n*(n+3)+1 are also twin primes.

3, 15, 495, 624, 1308, 1365, 1494, 1659, 1848, 6363, 8064, 12780, 13908, 14013, 16530, 18018, 18654, 28575, 30885, 31020, 38130, 43674, 48735, 50379, 57198, 60915, 61059, 62943, 75768, 76359, 76569, 80949, 81075, 83028, 84045, 86085, 88185, 104664, 105588

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..10000 (first 500 terms from Pierre CAMI)

Example

3*4=12: 11 and 13 are twin primes; 3*6=18 and 17 and 19 are also twin primes.

Prog

(PARI) isok(n) = isprime(n*(n+1)-1) && isprime(n*(n+1)+1) && isprime(n*(n+3)-1) &&  isprime(n*(n+3)+1); \\ Michel Marcus, Sep 23 2019

Crossrefs

Subsequence of A088485.

Sequence in context: A193119 A309069 A122579 * A338293 A267096 A217449

Adjacent sequences: A138300 A138301 A138302 * A138304 A138305 A138306

Keyword

nonn

Author

Pierre CAMI, Mar 13 2008

Status

approved