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 A088878 Prime numbers p such that 3p - 2 is a prime. 44
 3, 5, 7, 11, 13, 23, 37, 43, 47, 53, 61, 67, 71, 103, 113, 127, 137, 163, 167, 181, 191, 193, 211, 251, 257, 263, 271, 277, 293, 307, 313, 331, 337, 347, 373, 401, 431, 433, 443, 461, 467, 487, 491, 523, 541, 557, 587, 593, 601, 673, 677, 727, 751, 757, 761 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Indices of semiprime octagonal numbers. - Jonathan Vos Post, Feb 16 2006 Daughter primes of order 1. - Artur Jasinski, Dec 12 2007 A010051(3*a(n)-2) = 1. - Reinhard Zumkeller, Jul 02 2015 REFERENCES M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988 Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Eric Weisstein's World of Mathematics, Octagonal Number. Eric Weisstein's World of Mathematics, Semiprime. EXAMPLE For p = 3, 3p - 2 = 7; for p = 523, 3p - 2 = 1567. MATHEMATICA lst={}; Do[p=Prime[n]; If[PrimeQ[3*p-2], AppendTo[lst, p]], {n, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Dec 22 2008 *) n = 1; a = {}; Do[If[PrimeQ[(Prime[k] + 2n)/(2n + 1)], AppendTo[a, (Prime[k] + 2n)/(2n + 1)]], {k, 1, 500}]; a (* Artur Jasinski, Dec 12 2007 *) PROG (Magma) [ p: p in PrimesUpTo(770) | IsPrime(3*p-2) ]; // Klaus Brockhaus, Dec 21 2008 (PARI) list(lim)=select(p->isprime(3*p-2), primes(primepi(lim))) \\ Charles R Greathouse IV, Jul 25 2011 (Haskell) a088878 n = a088878_list !! (n-1) a088878_list = filter ((== 1) . a010051' . subtract 2 . (* 3)) a000040_list -- Reinhard Zumkeller, Jul 02 2015 CROSSREFS Cf. A000040, A000567, A001222, A001358, A091179, A091180, A091181, A136019, A136020, A153183, A153184. Cf. A010051, A063908, A172287. Cf. A259730. Sequence in context: A350401 A154319 A080114 * A259730 A254673 A343976 Adjacent sequences: A088875 A088876 A088877 * A088879 A088880 A088881 KEYWORD easy,nonn AUTHOR Giovanni Teofilatto, Nov 27 2003 EXTENSIONS Corrected and extended by Ray Chandler, Dec 27 2003 Entry revised by N. J. A. Sloane, Nov 28 2006, Jul 08 2010 STATUS approved

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Last modified February 8 00:00 EST 2023. Contains 360133 sequences. (Running on oeis4.)