A088765 a(n) = A087696(n)/2.

4, 6, 9, 12, 18, 21, 24, 33, 39, 42, 51, 54, 66, 72, 81, 84, 93, 114, 117, 123, 138, 144, 156, 171, 177, 189, 192, 207, 213, 219, 222, 231, 252, 276, 291, 306, 318, 324, 339, 348, 357, 369, 378, 396, 408, 417, 429, 441, 462, 471, 486, 507, 513, 522, 528, 546

Offset

1,1

Comments

"Example 3: Ordinary twins 2a +- 1 for a = 2, 3, 6, 9, 15, . . . have D = 1 and are in class I. For D = 3, the twins 2a +- 3 occur for a = 4, 5, 7, 8, 10"; the latter is this sequence, from p. 3 of Weber. - Jonathan Vos Post, Feb 14 2011

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..3100

H. J. Weber, Exceptional Prime Number Twins, Triplets and Multiplets, arXiv:1102.3075 [math.NT], 2011.

Mathematica

Select[Range[3, 2000], PrimeQ[# + 5] && PrimeQ[# - 5] &] / 2 (* Vincenzo Librandi, May 20 2017 *)

Prog

(Magma) [n/2: n in [3..2000] |IsPrime(n+5) and IsPrime(n-5)]; // Vincenzo Librandi, May 20 2017

Crossrefs

Cf. A087696, A040040, A088763, A088767, A088769.

Sequence in context: A185595 A310669 A310670 * A175250 A078782 A165897

Adjacent sequences: A088762 A088763 A088764 * A088766 A088767 A088768

Keyword

nonn

Author

Ray Chandler, Oct 26 2003

Extensions

Offset changed from 0 to 1 by Vincenzo Librandi, May 21 2017

Status

approved