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A061668
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Numbers n such that x-4, x-2, x+2, x+4 are primes, where x = 30*n - 15.
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1
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1, 4, 7, 28, 50, 63, 70, 109, 116, 189, 315, 434, 522, 525, 536, 602, 631, 648, 701, 743, 844, 1058, 1162, 1460, 1712, 1845, 2100, 2241, 2317, 2408, 2576, 2657, 2702, 2758, 2961, 3262, 3305, 3371, 3662, 3885, 3977, 4074, 4516, 4806, 5243, 5524, 5562, 5706
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Ignoring (5,7,11,13) another name for this sequence could be "twin prime twins".
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
| 4 is in the sequence because 101, 103, 107, 109 are primes and 105= 4*30-15.
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MATHEMATICA
| p4Q[n_]:=Module[{c=30n-15}, And@@PrimeQ[{c-4, c-2, c+2, c+4}]]; Select[ Range[ 6000], p4Q] (* From Harvey P. Dale, Dec 04 2011 *)
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PROG
| (PARI) { n=0; for (a=1, 391335, x=30*a - 15; if (isprime(x-4) && isprime(x-2) && isprime(x+2) && isprime(x+4), write("b061668.txt", n++, " ", a)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 26 2009]
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CROSSREFS
| 30 * a(n) = A007530(n+1) + 19.
Sequence in context: A076148 A203570 A146085 * A128386 A149074 A149075
Adjacent sequences: A061665 A061666 A061667 * A061669 A061670 A061671
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KEYWORD
| easy,nonn
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AUTHOR
| Frank.Ellermann(AT)t-online.de, Jun 15 2001
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EXTENSIONS
| More terms from Larry Reeves (larryr(AT)acm.org), Jun 20 2001
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