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!)
 A122007 Expansion of 2*x^2*(1-2*x) / ((3*x-1)*(3*x^2-1)). 1
 0, 2, 2, 12, 24, 90, 234, 756, 2160, 6642, 19602, 59292, 176904, 532170, 1593594, 4785156, 14346720, 43053282, 129133602, 387440172, 1162241784, 3486843450, 10460294154, 31381236756, 94143001680, 282430067922, 847288078002, 2541867422652, 7625595890664 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES "Linear Algebra, Examples and Applications" by Alain M. Robert, World Scientific, 2005, p. 58. LINKS Colin Barker, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (3,3,-9). FORMULA Limit a(n+1)/a(n)= 3 as n-> infinity. a(n)= 3*a(n-1) +3*a(n-2) -9*a(n-3) = 3^(n-2) + (-1)^n*A108411(n-2), n>=2. From Colin Barker, Sep 23 2016: (Start) a(n) = 3^(n/2-1)+3^(n-2) for n>1 and even. a(n) = 3^(n-2)-3^((n-3)/2) for n>1 and odd. (End) MATHEMATICA M = {{0, 1, 2}, {1, 2, 0}, {2, 0, 1}} v[1] = {1, 0, 0} v[n_] := v[n] = M.v[n - 1] a1 = Table[v[n][[3]], {n, 1, 50}] PROG (PARI) concat(0, Vec(2*x^2*(1-2*x)/((3*x-1)*(3*x^2-1)) + O(x^40))) \\ Colin Barker, Sep 23 2016 CROSSREFS Sequence in context: A092900 A303537 A164961 * A137782 A131384 A052612 Adjacent sequences:  A122004 A122005 A122006 * A122008 A122009 A122010 KEYWORD nonn,easy AUTHOR Roger L. Bagula and Gary W. Adamson, Sep 11 2006 EXTENSIONS Definition replaced with generating function by the Assoc. Eds. of the OEIS, Mar 27 2010 A-number in formula corrected - R. J. Mathar, Mar 30 2010 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 February 26 08:15 EST 2020. Contains 332277 sequences. (Running on oeis4.)