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.

A015548 Expansion of x/(1 - 5*x - 12*x^2).

Original entry on oeis.org

0, 1, 5, 37, 245, 1669, 11285, 76453, 517685, 3505861, 23741525, 160777957, 1088788085, 7373275909, 49931836565, 338138493733, 2289874507445, 15507034462021, 105013666399445, 711152745541477, 4815927724500725, 32613471569001349
Offset: 0

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Author

Keywords

Crossrefs

Cf. A015564 (binomial transform).

Programs

  • Magma
    [n le 2 select n-1 else 5*Self(n-1) + 12*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 13 2012
    
  • Mathematica
    Join[{a=0,b=1},Table[c=5*b+12*a;a=b;b=c,{n,100}]] (* Vladimir Joseph Stephan Orlovsky, Jan 16 2011 *)
    LinearRecurrence[{5, 12}, {0, 1}, 30] (* Vincenzo Librandi, Nov 13 2012 *)
    CoefficientList[Series[x/(1-5x-12x^2),{x,0,30}],x] (* Harvey P. Dale, May 27 2023 *)
  • PARI
    x='x+O('x^30); concat([0], Vec(x/(1-5*x-12*x^2))) \\ G. C. Greubel, Jan 16 2018
  • Sage
    [lucas_number1(n,5,-12) for n in range(0, 21)] # Zerinvary Lajos, Apr 24 2009
    

Formula

a(n) = 2*A099919(n-1) + 1, for n>=1.
a(n) = 5 a(n-1) + 12 a(n-2).

A189800 a(n) = 6*a(n-1) + 8*a(n-2), with a(0)=0, a(1)=1.

Original entry on oeis.org

0, 1, 6, 44, 312, 2224, 15840, 112832, 803712, 5724928, 40779264, 290475008, 2069084160, 14738305024, 104982503424, 747801460736, 5326668791808, 37942424436736, 270267896954880, 1925146777223168, 13713023838978048, 97679317251653632, 695780094221746176
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Magma
    I:=[0,1]; [n le 2 select I[n] else 6*Self(n-1)+8*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 14 2011
    
  • Mathematica
    LinearRecurrence[{6, 8}, {0, 1}, 50]
    CoefficientList[Series[-(x/(-1+6 x+8 x^2)),{x,0,50}],x] (* Harvey P. Dale, Jul 26 2011 *)
  • PARI
    a(n)=([0,1; 8,6]^n*[0;1])[1,1] \\ Charles R Greathouse IV, Oct 03 2016

Formula

G.f.: x/(1 - 2*x*(3+4*x)). - Harvey P. Dale, Jul 26 2011

A287815 Number of octonary sequences of length n such that no two consecutive terms have distance 7.

Original entry on oeis.org

1, 8, 62, 482, 3746, 29114, 226274, 1758602, 13667858, 106226618, 825593474, 6416514026, 49869159026, 387583197338, 3012297335522, 23411580532682, 181954847741906, 1414153417389434, 10990803008177474, 85420541561578922, 663888608980117298, 5159743512230294618
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Examples

			For n=2 the a(2) = 64 - 2 = 62 sequences contain every combination except these two: 07,70.
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{7, 6}, {1, 8}, 40]
  • Python
    def a(n):
     if n in [0, 1]:
      return [1, 8][n]
     return 7*a(n-1)+6*a(n-2)

Formula

a(n) = 7*a(n-1) + 6*a(n-2), a(0)=1, a(1)=8.
G.f.: (-1 - x)/(-1 + 7 x + 6 x^2).
a(n) = A015564(n)+A015564(n+1). - R. J. Mathar, Oct 20 2019
Showing 1-3 of 3 results.