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.

A124313 Pentanacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) + a(n-5), starting 1,0,0,0,1.

Original entry on oeis.org

1, 0, 0, 0, 1, 2, 3, 6, 12, 24, 47, 92, 181, 356, 700, 1376, 2705, 5318, 10455, 20554, 40408, 79440, 156175, 307032, 603609, 1186664, 2332920, 4586400, 9016625, 17726218, 34848827, 68510990, 134689060, 264791720, 520566815, 1023407412
Offset: 1

Views

Author

Artur Jasinski, Oct 25 2006

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( x*(1-2*x+x^4)/(1-2*x+x^6) )); // G. C. Greubel, Aug 25 2023
    
  • Mathematica
    f[n_]:= MatrixPower[{{1,1,1,1,1}, {1,0,0,0,0}, {0,1,0,0,0}, {0,0,1,0, 0}, {0,0,0,1,0}}, n][[ 1, 4]]; Array[f, 50]
    LinearRecurrence[{1,1,1,1,1}, {1,0,0,0,1}, 40] (* G. C. Greubel, Aug 25 2023 *)
  • SageMath
    def A124313_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1-2*x+x^4)/(1-2*x+x^6) ).list()
    A124313_list(50) # G. C. Greubel, Aug 25 2023

Formula

G.f.: x*(1-x-x^2-x^3)/(1-x-x^2-x^3-x^4-x^5). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 12 2009; checked and corrected by R. J. Mathar, Sep 16 2009

Extensions

Edited by Ralf Stephan, Oct 20 2013

A124314 Expansion of -1/(1 + x + x^2 + x^3 + x^4 - x^5).

Original entry on oeis.org

-1, 1, 0, 0, 0, -2, 3, -1, 0, 0, -4, 8, -5, 1, 0, -8, 20, -18, 7, -1, -16, 48, -56, 32, -9, -31, 112, -160, 120, -50, -53, 255, -432, 400, -220, -56, 563, -1119, 1232, -840, 108, 1182, -2801, 3583, -2912, 1056, 2256, -6784, 9967, -9407, 5024
Offset: 0

Views

Author

Artur Jasinski, Oct 25 2006

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 60); Coefficients(R!( (-1+x)/(1-2*x^5+x^6) )); // G. C. Greubel, Aug 25 2023
    
  • Mathematica
    CoefficientList[Series[1/(-1-x-x^2-x^3-x^4+x^5), {x,0,50}], x]
    LinearRecurrence[{-1,-1,-1,-1,1}, {-1,1,0,0,0}, 60] (* G. C. Greubel, Aug 25 2023 *)
  • PARI
    Vec(1/(-1-x-x^2-x^3-x^4+x^5)+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
    
  • SageMath
    def A124314_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (-1+x)/(1-2*x^5+x^6) ).list()
    A124314_list(60) # G. C. Greubel, Aug 25 2023

A251653 5-step Fibonacci sequence starting with 0,0,1,0,0.

Original entry on oeis.org

0, 0, 1, 0, 0, 1, 2, 4, 7, 14, 28, 55, 108, 212, 417, 820, 1612, 3169, 6230, 12248, 24079, 47338, 93064, 182959, 359688, 707128, 1390177, 2733016, 5372968, 10562977, 20766266, 40825404, 80260631, 157788246, 310203524, 609844071, 1198921876, 2357018348, 4633776065, 9109763884, 17909324244, 35208804417
Offset: 0

Views

Author

Arie Bos, Dec 06 2014

Keywords

Comments

Doubling the entries > 1 as 1, 2, 2, 4, 4, 7, 7, 14, 14, 28, 28, 55, 55,... (offset 0) gives Nyblom's palindromic binary strings having no 5-runs of 1's. - R. J. Mathar, Mar 28 2025

Crossrefs

Programs

  • J
    (see www.jsoftware.com) First construct the generating matrix
    1  1  1  1  1
    1  2  2  2  2
    2  3  4  4  4
    4  6  7  8  8
    8 12 14 15 16
    Given that matrix one can produce the first 5*200 numbers by
    , M(+/ . *)^:(i.250) 0 0 1 0 0x
  • Mathematica
    LinearRecurrence[{1, 1, 1, 1, 1}, {0, 0, 1, 0, 0}, 100] (* G. C. Greubel, May 27 2016 *)

Formula

a(n+5) = a(n) + a(n+1) + a(n+2) + a(n+3) + a(n+4).
G.f.: x^2*(x^2 + x - 1)/(x^5 + x^4 + x^3 + x^2 + x - 1). - Chai Wah Wu, May 27 2016
Showing 1-3 of 3 results.