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 A168398 a(n) = 4 + 8*floor((n-1)/2). 2
 4, 4, 12, 12, 20, 20, 28, 28, 36, 36, 44, 44, 52, 52, 60, 60, 68, 68, 76, 76, 84, 84, 92, 92, 100, 100, 108, 108, 116, 116, 124, 124, 132, 132, 140, 140, 148, 148, 156, 156, 164, 164, 172, 172, 180, 180, 188, 188, 196, 196, 204, 204, 212, 212, 220, 220, 228, 228 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA a(n) = 8*n - a(n-1) - 8, with n>1, a(1)=4. a(n) = -2 -2*(-1)^n + 4*n. - Paolo P. Lava, Nov 27 2009 G.f.: 4*x*(1 + x^2)/((1+x)*(x-1)^2). - Vincenzo Librandi, Sep 18 2013 a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 18 2013 a(n) = 4 * A109613(n-1). - Bruno Berselli, Sep 18 2013 E.g.f.: 4*(1 + (x - 1)*cosh(x) + x*sinh(x)). - G. C. Greubel, Jul 20 2016 MATHEMATICA Table[4 + 8*Floor[(n - 1)/2], {n, 60}] (* Vincenzo Librandi, Sep 18 2013 *) PROG (MAGMA) [4+8*Floor((n-1)/2): n in [1..70]]; // Vincenzo Librandi, Sep 18 2013 CROSSREFS Cf. A017113, A109613. Sequence in context: A273412 A206488 A273491 * A281913 A178776 A282503 Adjacent sequences:  A168395 A168396 A168397 * A168399 A168400 A168401 KEYWORD nonn,easy,less AUTHOR Vincenzo Librandi, Nov 25 2009 EXTENSIONS New definition by Vincenzo Librandi, Sep 18 2013 STATUS approved

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Last modified August 24 23:53 EDT 2019. Contains 326314 sequences. (Running on oeis4.)