This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A063757 G.f.: (1+3*x+2*x^2)/((1-x)*(1-2*x^2)). 3
 1, 4, 8, 14, 22, 34, 50, 74, 106, 154, 218, 314, 442, 634, 890, 1274, 1786, 2554, 3578, 5114, 7162, 10234, 14330, 20474, 28666, 40954, 57338, 81914, 114682, 163834, 229370, 327674, 458746, 655354, 917498, 1310714, 1835002, 2621434 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES P. de la Harpe, Topics in Geometric Group Theory, Univ. Chicago Press, 2000, p. 158. LINKS Index entries for linear recurrences with constant coefficients, signature (1,2,-2). FORMULA a(0)=1, a(1)=4, a(2)=8, a(n)=a(n-1)+2*a(n-2)-2*a(n-3) From Harvey P. Dale, Jun 05 2012 a(n)=2^((n-3)/2)*((5*Sqrt[2]-7)*(-1)^n+7+5*Sqrt[2])-6 From Harvey P. Dale, Jun 05 2012 a(2*n) = 7*2^n - 6 = A048489(n), a(2*n+1) = 10*2^n - 6 = A020714(n+1) - 6, a(n) = A070875(n+1) - 6. - Philippe Deléham, Apr 13 2013 MATHEMATICA CoefficientList[Series[(1+3x+2x^2)/((1-x)(1-2x^2)), {x, 0, 40}], x] (* or *) LinearRecurrence[{1, 2, -2}, {1, 4, 8}, 41] (* Harvey P. Dale, Jun 05 2012 *) CROSSREFS Sequence in context: A011897 A110895 A049628 * A193711 A079328 A073612 Adjacent sequences:  A063754 A063755 A063756 * A063758 A063759 A063760 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Aug 14 2001 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.