The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A185647 Expansion of (1+2x)*(1+2*x^2)/((1-x)*(1+x)*(1-2*x^2)). 1
 1, 2, 5, 10, 13, 26, 29, 58, 61, 122, 125, 250, 253, 506, 509, 1018, 1021, 2042, 2045, 4090, 4093, 8186, 8189, 16378, 16381, 32762, 32765, 65530, 65533, 131066, 131069, 262138, 262141, 524282, 524285, 1048570, 1048573, 2097146, 2097149, 4194298, 4194301 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..5000 Index entries for linear recurrences with constant coefficients, signature (0,3,0,-2). FORMULA a(n) = a(n-1)*2 if n odd. a(n) = a(n-1)+3 if n even. a(2n) = 2^(n+2)-3 = A036563(n+2). a(2n+1) = 2^(n+3)-6 = A131130(n+1). a(n) = 3*a(n-2) - 2*a(n-4) with a(0)=1, a(1)=2, a(2)=5, a(3)=10. MATHEMATICA LinearRecurrence[{0, 3, 0, -2}, {1, 2, 5, 10}, 50] (* G. C. Greubel, Jul 09 2017 *) PROG (PARI) x='x+O('x^50); Vec((1+2*x)*(1+2*x^2)/((1-x)*(1+x)*(1-2*x^2))) \\ G. C. Greubel, Jul 09 2017 CROSSREFS Cf. A036563, A131130 Sequence in context: A051952 A103188 A281229 * A064392 A328700 A018296 Adjacent sequences:  A185644 A185645 A185646 * A185648 A185649 A185650 KEYWORD nonn,easy AUTHOR Philippe Deléham, Apr 23 2013 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 29 09:41 EDT 2021. Contains 346344 sequences. (Running on oeis4.)