A076504 Numbers k such that (k-1, k+1) and (k/2-1, k/2+1) are both pairs of twin primes.

12, 60, 1320, 1620, 4260, 5100, 6660, 6780, 11700, 12540, 21060, 66360, 83220, 88260, 107100, 110880, 114660, 127680, 130200, 140760, 141960, 144540, 148200, 149520, 157560, 161340, 163860, 175080, 186480, 204600, 230940, 249540

Offset: 1

Author

Eric W. Weisstein, Oct 15 2002

Keywords

• nonn

Comments

Terms after the first are multiples of 60. - Marc Morgenegg, Apr 19 2016

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A066388.

Programs

Mathematica

Select[Mean /@ Select[Partition[Prime[Range[30000]], 2, 1], Last[#] - First[#] == 2 &], And @@ PrimeQ[#/2 + {1, -1}] &] (* Harvey P. Dale, Jan 23 2014 *)

Formula

a(n) = 2*A066388(n).

Extensions

Definition corrected by Jaroslav Krizek, Apr 12 2009