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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A013983 Expansion of 1/(1-x^2-x^3-x^4-x^5-x^6).

Original entry on oeis.org

1, 0, 1, 1, 2, 3, 5, 7, 12, 18, 29, 45, 71, 111, 175, 274, 431, 676, 1062, 1667, 2618, 4110, 6454, 10133, 15911, 24982, 39226, 61590, 96706, 151842, 238415, 374346, 587779, 922899, 1449088, 2275281, 3572527
Offset: 0

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Author

Keywords

Comments

Number of compositions of n into parts p where 2 <= p < = 6. [Joerg Arndt, Jun 24 2013]

Crossrefs

First differences of A023437.

Programs

  • Magma
    m:=40; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^2-x^3-x^4-x^5-x^6))); // Vincenzo Librandi, Jun 24 2013
  • Mathematica
    CoefficientList[Series[1 / (1 - x^2 - x^3 - x^4 - x^5 - x^6), {x, 0, 50}], x] (* Vincenzo Librandi, Jun 23 2013 *)
    LinearRecurrence[{0,1,1,1,1,1},{1,0,1,1,2,3},50] (* Harvey P. Dale, Dec 31 2013 *)
  • PARI
    Vec(1/(1-x^2-x^3-x^4-x^5-x^6)+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
    

Formula

a(n) = a(n-6) + a(n-5) + a(n-4) + a(n-3) + a(n-2). - Jon E. Schoenfield, Aug 07 2006
G.f.: 1 / ( (1+x)*(1-x^5-x^3-x)). a(n)+a(n+1) = A060961(n). - R. J. Mathar, Mar 22 2011

A171997 a(n) = a(n-1) + a(n-2) - floor(a(n-2)/2) - floor(a(n-5)/2); initial terms are 1, 1, 2, 3, 4.

Original entry on oeis.org

1, 1, 2, 3, 4, 6, 8, 10, 13, 16, 20, 24, 29, 35, 42, 50, 59, 70, 83, 97, 114, 134, 156, 182, 212, 246, 285, 330, 382, 441, 509, 588, 678, 781, 900, 1037, 1193, 1373, 1580, 1817, 2089, 2402, 2761, 3172, 3645, 4187, 4809, 5523, 6342, 7282, 8360
Offset: 1

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Author

Roger L. Bagula, Nov 22 2010

Keywords

Comments

lim_{n -> infinity} a(n+1)/a(n) = 1.14710876512065387719410850648860644150605499412513....
a(n) = A062435(n+2) for n < 15.

Crossrefs

Cf. A062435 (integer part of log(n!)^log(log(1 + n))), A023434 (a(n)=a(n-1)+a(n-2)-a(n-4)), A023435 (a(n)=a(n-1)+a(n-2)-a(n-5)), A023436 (a(n)=a(n-1)+a(n-2)-a(n-6)), A023437 (a(n)=a(n-1)+a(n-2)-a(n-7)), A023438 (a(n)=a(n-1)+a(n-2)-a(n-8)), A023439 (a(n)=a(n-1)+a(n-2)-a(n-9)), A023440 (a(n)=a(n-1)+a(n-2)+a(n-10)), A023441 (a(n)=a(n-1)+a(n-2)-a(n-11)), A023442 (a(n)=a(n-1)+a(n-2)-a(n-12)), A000044 (a(n)=a(n-1)+a(n-2)-a(n-13)), A173199 (a(n)=a(n-1)+a(n-2)-floor(a(n-3)/2)-floor(a(n-8)/2)).

Programs

  • Magma
    I:=[1,1,2,3,4]; [n le 5 select I[n] else Self(n-1) + Self(n-2) - Floor(Self(n-2)/2) - Floor(Self(n-5)/2): n in [1..60]]; // Vincenzo Librandi, Jun 24 2015
  • Mathematica
    f[-3] = 0; f[-2] = 0; f[-1] = 0; f[0] = 1; f[1] = 1;
    f[n_] := f[n] = f[n - 1] + f[n - 2] - Floor[f[n - 2]/2] - Floor[f[n - 5]/2]
    Table[f[n], {n, 0, 50}]

Extensions

Offset changed from 0 to 1 by Klaus Brockhaus, Nov 29 2010
Showing 1-2 of 2 results.