cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A081552 Leading terms of rows in A081551.

Original entry on oeis.org

1, 11, 102, 1003, 10004, 100005, 1000006, 10000007, 100000008, 1000000009, 10000000010, 100000000011, 1000000000012, 10000000000013, 100000000000014, 1000000000000015, 10000000000000016, 100000000000000017, 1000000000000000018
Offset: 1

Views

Author

Amarnath Murthy, Apr 01 2003

Keywords

Comments

More generally, a(n) = B^K + n; K = floor(log_B a(n-1)) + 1. This sequence has B=10, a(0)=1; A006127 has B=2, a(0)=1; A052944 has B=2, a(0)=2; A104743 has B=3, a(0)=1; A104745 has B=5, a(0)=1. - Ctibor O. Zizka, Mar 22 2008

Crossrefs

Cf. A011557, A081551, A081553, A085952 (first differences, after n=2).

Programs

  • Magma
    [10^(n-1)+n-1: n in [1..20]]; // Vincenzo Librandi, Jun 16 2013
    
  • Magma
    I:=[1, 11, 102]; [n le 3 select I[n] else 12*Self(n-1)-21*Self(n-2)+10*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Jun 16 2013
    
  • Maple
    seq(10^(n-1) +n-1, n=1..40); # G. C. Greubel, May 27 2021
  • Mathematica
    Table[10^(n-1) +n-1, {n,30}] (* or *) CoefficientList[Series[(1-x-9x^2)/((1-10x)(1-x)^2), {x, 0, 30}], x]  (* Vincenzo Librandi, Jun 16 2013 *)
  • Sage
    [10^(n-1) +n-1 for n in (1..40)] # G. C. Greubel, May 27 2021

Formula

a(n) = 10^(n-1) + n-1.
G.f.: x*(1 -x -9*x^2)/((1-10*x)*(1-x)^2). - Vincenzo Librandi, Jun 16 2013
a(n) = 12*a(n-1) -21*a(n-2) +10*a(n-3). - Vincenzo Librandi, Jun 16 2013
E.g.f.: (1/10)*(9 - 10*(1-x)*exp(x) + exp(10*x)). - G. C. Greubel, May 27 2021

A085951 For n <= 5, a(n) = 2n-1. For n > 5, a(n) is the least odd number not already used that begins with the last digit of a(n-1).

Original entry on oeis.org

1, 3, 5, 7, 9, 91, 11, 13, 31, 15, 51, 17, 71, 19, 93, 33, 35, 53, 37, 73, 39, 95, 55, 57, 75, 59, 97, 77, 79, 99, 901, 101, 103, 301, 105, 501, 107, 701, 109, 903, 303, 305, 503, 307, 703, 309, 905, 505, 507, 705, 509, 907, 707, 709, 909, 911, 111, 113, 311, 115, 511
Offset: 1

Views

Author

Amarnath Murthy and Jason Earls, Jul 15 2003

Keywords

Crossrefs

Cf. A085952.

Extensions

Corrected and extended by David Wasserman, Feb 15 2005
Edited by Charles R Greathouse IV, Aug 03 2010
Showing 1-2 of 2 results.