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A163634 a(n) = (p*(p+4)+1)/2 where (p,p+4) are the n-th cousin prime pair. 1
11, 39, 111, 219, 759, 1011, 2379, 3279, 4899, 5511, 6159, 8319, 13611, 19011, 25311, 26679, 38919, 47739, 49611, 61599, 72579, 79599, 97239, 105339, 108111, 119559, 125499, 189111, 208011, 227811, 274539, 288039, 297219, 340311, 365511, 370659 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..112

FORMULA

a(n) = (A143206(n) + 1)/2.

EXAMPLE

a(1) =  (3* 7 + 1)/2 =  11;

a(2) =  (7*11 + 1)/2 =  39;

a(3) = (13*17 + 1)/2 = 111.

MATHEMATICA

(fQ[n_]:=Block[{fi=FactorInteger@n}, Last@#&/@fi=={1, 1}&&Differences[First@#&/@fi]=={4}]; Select[Range@8000000, fQ] + 1)/2 (* Vincenzo Librandi Jan 02 2018 *)

PROG

(MAGMA) [(p*(p+4)+1)/2: p in PrimesUpTo(1000)| IsPrime(p+4)]; // Vincenzo Librandi, May 17 2014

CROSSREFS

Cf. A023200, A046132.

Sequence in context: A045801 A162261 A004188 * A173373 A127867 A138050

Adjacent sequences:  A163631 A163632 A163633 * A163635 A163636 A163637

KEYWORD

nonn

AUTHOR

Vincenzo Librandi, Aug 02 2009

EXTENSIONS

Entries checked by R. J. Mathar, Aug 07 2009

STATUS

approved

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Last modified March 19 13:08 EDT 2019. Contains 321330 sequences. (Running on oeis4.)