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A076504 Numbers n such that (n-1, n+1) and (n/2-1, n/2+1) are both pairs of twin primes. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that n - 1, n + 1 are twin primes and n - 2, n + 2 are squarefree semiprimes. - Paolo P. Lava, Jul 03 2015

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

FORMULA

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

MATHEMATICA

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

CROSSREFS

Cf. A066388.

Sequence in context: A056388 A056378 A231026 * A232700 A044150 A044531

Adjacent sequences:  A076501 A076502 A076503 * A076505 A076506 A076507

KEYWORD

nonn

AUTHOR

Eric W. Weisstein, Oct 15 2002

EXTENSIONS

Definition corrected. - Jaroslav Krizek, Apr 12 2009

STATUS

approved

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Last modified July 22 20:51 EDT 2019. Contains 325226 sequences. (Running on oeis4.)