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

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A132583 a(n) = n 2's sandwiched between two 1's. 3
 11, 121, 1221, 12221, 122221, 1222221, 12222221, 122222221, 1222222221, 12222222221, 122222222221, 1222222222221, 12222222222221, 122222222222221, 1222222222222221, 12222222222222221, 122222222222222221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..500 Index entries for linear recurrences with constant coefficients, signature (11, -10). FORMULA a(0) = 11; a(n) = 10*a(n-1) + 11. - Jonathan Vos Post, Nov 24 2007 [corrected by Jon E. Schoenfield, Jan 28 2018] O.g.f.: 11/((-1+x)*(-1+10*x)) = -(110/9)/(-1+10*x)+(11/9)/(-1+x). - R. J. Mathar, Nov 28 2007 a(n) = 20*(10^n-1)/9 + 10^(n+1)+1, with n>=0. - Paolo P. Lava, Dec 19 2007 MAPLE g:=(1+z)/((1-z)*(1-10*z)): gser:=series(g, z=0, 43): seq((coeff(gser, z, n))-1, n=1..24); # Zerinvary Lajos, Feb 25 2009 MATHEMATICA NestList[10#+11&, 11, 20] (* or *) LinearRecurrence[{11, -10}, {11, 121}, 20] (* Harvey P. Dale, Sep 24 2012 *) PROG (MAGMA) [20*(10^n-1)/9+10^(n+1)+1: n in [0..25]]; // Vincenzo Librandi, Aug 10 2011 CROSSREFS Sequence in context: A106473 A125315 A223676 * A007907 A171285 A216132 Adjacent sequences:  A132580 A132581 A132582 * A132584 A132585 A132586 KEYWORD nonn,base,easy AUTHOR Paul Curtz, Nov 21 2007 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 December 6 10:24 EST 2021. Contains 349563 sequences. (Running on oeis4.)