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A129521
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Numbers of the form p*q, p and q prime with q=2*p-1.
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6
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6, 15, 91, 703, 1891, 2701, 12403, 18721, 38503, 49141, 79003, 88831, 104653, 146611, 188191, 218791, 226801, 269011, 286903, 385003, 497503, 597871, 665281, 721801, 736291, 765703, 873181, 954271, 1056331, 1314631, 1373653, 1537381
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) = A005382(n)*A005383(n);
subsequence of A006881 and of A129510.
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LINKS
| David W. Wilson, Table of n, a(n) for n = 1..1000
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MATHEMATICA
| p = Select[Prime[Range[155]], PrimeQ[2# - 1] &]; p (2p - 1) (* Robert G. Wilson v, Sept 11 2011 *)
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PROG
| (MAGMA)[2*n^2-n: n in [0..1000]|IsPrime(n) and IsPrime(2*n-1)]; [From Vincenzo Librandi, Dec 27 2010]
(PARI) forprime(p=2, 10000, q=2*p-1; if(isprime(q), print1(p*q, ", ")))
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CROSSREFS
| Cf. A141768, A191311, A191592.
Sequence in context: A013225 A138547 A194265 * A029765 A068128 A013222
Adjacent sequences: A129518 A129519 A129520 * A129522 A129523 A129524
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 19 2007
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