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A088765 a(n) = A087696(n)/2. 7
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 (list; graph; refs; listen; history; text; internal format)
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

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

STATUS

approved

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Last modified May 28 21:37 EDT 2020. Contains 334690 sequences. (Running on oeis4.)