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 A090658 Numbers n such that n-1 is a prime of the form 4k+3. 1
 4, 8, 12, 20, 24, 32, 44, 48, 60, 68, 72, 80, 84, 104, 108, 128, 132, 140, 152, 164, 168, 180, 192, 200, 212, 224, 228, 240, 252, 264, 272, 284, 308, 312, 332, 348, 360, 368, 380, 384, 420, 432, 440, 444, 464, 468, 480, 488, 492, 500, 504, 524, 548, 564, 572 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 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..5000 FORMULA a(n) = A087915(n)+A089257(n), A089193(n)+A089257(n)-5. MATHEMATICA okQ[n_]:=Module[{x=n-1}, PrimeQ[x]&&IntegerQ[(x-3)/4]]; Select[Range[1, 1000, 1], okQ] (* Vincenzo Librandi, Dec 13 2011 *) Select[4*Range[0, 200]+3, PrimeQ]+1 (* Harvey P. Dale, Sep 25 2017 *) CROSSREFS Cf. A002145, A087915, A089193, A089257. Sequence in context: A311656 A311657 A033691 * A268799 A269711 A122108 Adjacent sequences:  A090655 A090656 A090657 * A090659 A090660 A090661 KEYWORD easy,nonn AUTHOR Giovanni Teofilatto, Dec 14 2003 EXTENSIONS Corrected and extended by T. D. Noe, Oct 25 2006 STATUS approved

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Last modified April 6 18:32 EDT 2020. Contains 333286 sequences. (Running on oeis4.)