This site is supported by donations to The OEIS Foundation.

 Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS". Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A014113 a(n) = a(n-1) + 2*a(n-2) with a(0)=0, a(1)=2. 6
 0, 2, 2, 6, 10, 22, 42, 86, 170, 342, 682, 1366, 2730, 5462, 10922, 21846, 43690, 87382, 174762, 349526, 699050, 1398102, 2796202, 5592406, 11184810, 22369622, 44739242, 89478486, 178956970, 357913942 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 457 Index entries for linear recurrences with constant coefficients, signature (1,2). FORMULA a(0) = 0 and if n>=1, a(n) = 2^n - a(n-1). a(n) = A078008(n+1). - Reinhard Zumkeller, Jun 10 2005 a(n) = 2*A001045(n). - Benoit Jubin, Dec 01 2011 a(n) = (2^(n+1) - 2*(-1)^n)/3. - Ralf Stephan, Jul 18 2013 G.f.: 2*x/(1+x)/(1-2*x). - Colin Barker, Feb 19 2012 G.f.: 1/Q(0) -1, where Q(k) = 1 + 2*x^2 - (2*k+3)*x + x*(2*k+1 - 2*x)/Q(k+1); (continued fraction). - Sergei N. Gladkovskii, Oct 05 2013 MATHEMATICA LinearRecurrence[{1, 2}, {0, 2}, 50] (* Vincenzo Librandi, Feb 19 2012 *) PROG (Haskell) a014113 n = a014113_list !! n a014113_list = 0 : 2 : zipWith (+)                        (map (* 2) a014113_list) (tail a014113_list) -- Reinhard Zumkeller, Jul 20 2013 CROSSREFS Cf. A163271, A001045, A078008. Sequence in context: A167399 A247326 A019310 * A078008 A151575 A284462 Adjacent sequences:  A014110 A014111 A014112 * A014114 A014115 A014116 KEYWORD nonn,easy AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.