A127545 Multiples of 7, k, such that k +/- 1 are twin primes.

42, 420, 462, 882, 1050, 1092, 1302, 1428, 1722, 1932, 2142, 2268, 2310, 2688, 2730, 3360, 3528, 3822, 4158, 4242, 4788, 5418, 5502, 5880, 6090, 6132, 6300, 6552, 6762, 7308, 7350, 7560, 8232, 8820, 8862, 9240, 9282, 10038, 10332, 10458, 10500, 10710

Offset: 1

Author

Zak Seidov, Apr 01 2007

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Intersection of A008589 and A014574.

Programs

Mathematica

Select[Range[7,10710,7],PrimeQ[#-1]&&PrimeQ[#+1]&] (* James C. McMahon, Jan 01 2025 *)
Select[7 Range[2000],AllTrue[#+{1,-1},PrimeQ]&] (* Harvey P. Dale, Aug 16 2025 *)

PARI

a(n) = !(n %7) && isprime(n+1) && isprime(n-1); \\ Michel Marcus, Oct 11 2013

Extensions

Name edited by James C. McMahon, Jan 01 2025