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.

Showing 1-3 of 3 results.

A178512 Reversed decimal expansions of A178510.

Original entry on oeis.org

1, 121, 14521, 1742521, 209102521, 25092302521, 3011076302521, 361329156302521, 43359498756302521, 5203139850756302521, 624376782090756302521, 74925213850890756302521, 8991025662106890756302521, 1078923079452826890756302521, 129470769534339226890756302521
Offset: 1

Views

Author

Mark Dols, May 29 2010

Keywords

Comments

Related to backward decimal expansion of fraction 1/119 and Pell numbers. [How? - Joerg Arndt, May 14 2011]

Crossrefs

Programs

Formula

a(n) = 120*a(n-1) + 1.
From Colin Barker, Oct 02 2015: (Start)
a(n) = 121*a(n-1) - 120*a(n-2) for n > 2.
G.f.: x / ((x-1)*(120*x-1)).
(End)

A178511 a(n) = (1/119)*(100^n -(-19)^n).

Original entry on oeis.org

1, 81, 8461, 839241, 84054421, 8402966001, 840343645981, 84033470726361, 8403364056199141, 840336082932216321, 84033614424287889901, 8403361325938530091881, 840336134807167928254261, 84033613438663809363169041, 8403361344665387622099788221
Offset: 1

Views

Author

Mark Dols, May 29 2010

Keywords

Comments

Numerators in alternating Sum_{n>=0} 19^n/100^(n+1).
Related to decimal expansion of fraction of 1/119 and Pell numbers. [In which way? - Joerg Arndt, May 14 2011]

Crossrefs

Programs

  • Magma
    [(1/119)*(100^n -(-19)^n): n in [1..20]]; // Vincenzo Librandi, May 17 2011
    
  • Mathematica
    LinearRecurrence[{81,1900},{1,81},20] (* Harvey P. Dale, Nov 12 2022 *)
  • PARI
    Vec(-x/((19*x+1)*(100*x-1)) + O(x^20)) \\ Colin Barker, Oct 02 2015

Formula

a(n+1) = a(n)*100 +- 19^n with a(0)=0 and a(1)= 1.
From Colin Barker, Oct 02 2015: (Start)
a(n) = 81*a(n-1) + 1900*a(n-2) for n > 2.
G.f.: -x / ((19*x+1)*(100*x-1)).
(End)

A178513 Partial sums of 80^n.

Original entry on oeis.org

1, 81, 6481, 518481, 41478481, 3318278481, 265462278481, 21236982278481, 1698958582278481, 135916686582278481, 10873334926582278481, 869866794126582278481, 69589343530126582278481, 5567147482410126582278481, 445371798592810126582278481
Offset: 0

Views

Author

Mark Dols, May 29 2010

Keywords

Comments

Related to backward decimal expansion of fraction 1/79 and Pell numbers. [In which way? - Joerg Arndt, May 17 2011]

Crossrefs

Programs

  • Mathematica
    Accumulate[80^Range[0,20]] (* Harvey P. Dale, Aug 11 2014 *)

Formula

a(n) = 80*a(n-1) + 1.
a(n) = (80^(n+1)-1)/79.
G.f.: 1/((1-80*x)*(1-x)).
Showing 1-3 of 3 results.