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A261463
Numbers n such that n is a twin prime and 2n + 1 is a twin prime.
1
3, 5, 29, 659, 809, 2129, 2549, 3329, 3389, 5849, 6269, 10529, 33179, 41609, 44129, 53549, 55439, 57329, 63839, 65099, 70379, 70979, 72269, 74099, 74759, 78779, 80669, 81929, 87539, 93239, 102299, 115469, 124769, 133979, 136949, 156419, 161459, 168449
OFFSET
1,1
COMMENTS
n is a Sophie Germain prime and a twin prime, and 2*n+1 is also a twin prime.
Apparently this contains 3 and the members of A069142. - R. J. Mathar, Aug 23 2015
LINKS
FORMULA
a(n+1) = A069142(n), n>=1. - G. C. Greubel, Aug 23 2015
EXAMPLE
809 is a term because 809 and 811 are twin primes, and 2*809+1 = 1619 is a prime and a twin prime with 1621.
MATHEMATICA
sgtpQ[n_]:=Module[{sgp=2n+1}, PrimeQ[sgp]&&AnyTrue[sgp+{2, -2}, PrimeQ]]; Select[Union[Flatten[Select[Partition[Prime[Range[25000]], 2, 1], #[[2]]- #[[1]] ==2&]]], sgtpQ] (* The program uses the AnyTrue function from Mathematica version 10 *)
p=PrimeQ; Select[Prime@ Range[10^5], p[2#+1] && (p[#+2] || p[#-2]) && (p[2#+3] || p[2#-1]) &] (* Giovanni Resta, Aug 20 2015 *)
CROSSREFS
Sequence in context: A060255 A316791 A154552 * A352913 A100857 A100856
KEYWORD
nonn
AUTHOR
Harvey P. Dale, Aug 20 2015
STATUS
approved