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 1-4 of 4 results.

A099531 Expansion of (1+x)^3/((1+x)^3+x^4).

Original entry on oeis.org

1, 0, 0, 0, -1, 3, -6, 10, -14, 15, -7, -20, 80, -188, 351, -549, 702, -622, -42, 1839, -5471, 11560, -20064, 29144, -33329, 21059, 27730, -142182, 355626, -689121, 1114937, -1490892, 1461360, -337220, -2996465, 10030587, -22226506, 39921442, -60118930, 72788383, -55703295, -31057776
Offset: 0

Views

Author

Paul Barry, Oct 20 2004

Keywords

Comments

Binomial transform is A099530.

Crossrefs

Cf. A099529.

Programs

  • Mathematica
    CoefficientList[Series[(1+x)^3/((1+x)^3+x^4),{x,0,50}],x] (* or *) LinearRecurrence[{-3,-3,-1,-1},{1,0,0,0},50] (* Harvey P. Dale, Feb 21 2016 *)

Formula

a(n)=-3a(n-1)-3a(n-2)-a(n-3)-a(n-4); a(n)=sum{j=0..n, sum{k=0..floor(j/4), C(n, j)(-1)^(n-j)C(j-3k, k)(-1)^k}}.

A290989 Expansion of x^6*(1 + x^3)/(1 - 4*x + 5*x^2 - x^3 - 2*x^4 + x^6 + x^7 - 2*x^8 + x^9).

Original entry on oeis.org

1, 4, 11, 26, 55, 109, 208, 389, 722, 1339, 2488, 4634, 8646, 16146, 30160, 56333, 105198, 196413, 366672, 684475, 1277701, 2385080, 4452277, 8311254, 15515091, 28963012, 54067156, 100930660, 188413624, 351723304, 656583197
Offset: 6

Views

Author

R. J. Mathar, Aug 16 2017

Keywords

Comments

This corresponds to S(213,1,x) of Langley if one uses Theorem 8. Note that all three expressions for S(213;t,x), S(213;1,x) and the series on page 22 are mutually incompatible, so we show the sequence one would most likely see in other publications.

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( x^6*(1+x^3)/((1-x)*(1-2*x+x^3-x^4)*(1-x+x^4)) )); // G. C. Greubel, Apr 12 2023
    
  • Mathematica
    DeleteCases[#, 0] &@ CoefficientList[Series[x^6*(1+x^3)/(1 -4x +5x^2 -x^3 -2x^4 +x^6 +x^7 -2x^8 +x^9), {x, 0, 36}], x] (* Michael De Vlieger, Aug 16 2017 *)
    LinearRecurrence[{4,-5,1,2,0,-1,-1,2,-1}, {1,4,11,26,55,109,208,389,722}, 80] (* Vincenzo Librandi, Aug 17 2017 *)
  • SageMath
    def A290989_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x^6*(1+x^3)/((1-x)*(1-x+x^4)*(1-2*x+x^3-x^4)) ).list()
    a=A290989_list(50); a[6:] # G. C. Greubel, Apr 12 2023

Formula

G.f.: x^6*(1 + x)*(1 - x + x^2)/((1 - x)*(1 - 2*x + x^3 - x^4)*(1 - x + x^4)).
a(n) = -2 + (1/19)*( 9*A099530(n+1) + 15*A099530(n) + 2*A099530(n-1) - A099530(n- 2) + 10*A059633(n+4) - 6*A059633(n+3) - 16*A059633(n+2) - A059633(n+1) ). - G. C. Greubel, Apr 12 2023

A193884 Expansion of o.g.f. (1-x^2)/(1-x+x^4).

Original entry on oeis.org

1, 1, 0, 0, -1, -2, -2, -2, -1, 1, 3, 5, 6, 5, 2, -3, -9, -14, -16, -13, -4, 10, 26, 39, 43, 33, 7, -32, -75, -108, -115, -83, -8, 100, 215, 298, 306, 206, -9, -307, -613, -819, -810, -503, 110, 929, 1739, 2242, 2132, 1203, -536, -2778, -4910, -6113, -5577
Offset: 0

Views

Author

Johannes W. Meijer, Aug 11 2011

Keywords

Comments

The Kn11 sums, see A180662, of triangle A108299 equal the terms of this sequence.

Crossrefs

Programs

  • Maple
    A193884 := proc(n) option remember: if n=0 then 1 elif n=1 then 1 elif n=2 then 0 elif n=3 then 0 elif n>=4 then procname(n-1)-procname(n-4) fi: end: seq(A193884(n), n=0..54);
  • Mathematica
    CoefficientList[Series[(1-x^2)/(1-x+x^4),{x,0,80}],x] (* or *) LinearRecurrence[{1,0,0,-1},{1,1,0,0},80] (* Harvey P. Dale, Jul 15 2020 *)

Formula

G.f.: (1+x)*(1-x)/(1-x+x^4).
a(n) = a(n-1)-a(n-4), a(0) = a(1) = 1, a(2) = a(3) = 0.
a(n) = A099530(n) - A099530(n-2).

A198862 Sum of the n-th antidiagonal in the triangle A192011.

Original entry on oeis.org

-1, 2, 2, 2, 3, 1, -1, -3, -6, -7, -6, -3, 3, 10, 16, 19, 16, 6, -10, -29, -45, -51, -41, -12, 33, 84, 125, 137, 104, 20, -105, -242, -346, -366, -261, -19, 327, 693, 954, 973, 646, -47, -1001, -1974, -2620, -2573, -1572, 402, 3022
Offset: 0

Views

Author

Paul Curtz, Oct 30 2011

Keywords

Comments

The current sequence and its successive differences are:
-1, 2, 2, 2, 3, 1, -1 ,-3, -6, -7, ...
3, 0, 0, 1, -2, -2, -2, -3, -1, 1, 3, 6, 7, 6, 3, -3, -10, -16, ...
-3, 0, 1, -3, 0, 0, -1, 2, 2, 2, 3, 1, -1, -3, -6, -7, -6, ...
3, 1, -4, 3, 0, -1, 3, 0, 0, 1, -2, -2, -2, -3, -1, 1, 3, 6, 7, ...
-2, -5, 7, -3, -1, 4, -3, 0, 1, -3, 0, 0, -1, 2, 2, 2, 3, 1, ...
-3, 12, -10, 2, 5, -7, 3, 1, -4, 3, 0, -1, 3, 0, 0, 1, -2, ...
15, -22, 12, 3, -12, 10, -2, -5, 7, -3, -1, 4, -3, 0, ...
-37, 34, -9, -15, 22, -12, -3, 12, -10, 2, 5, -7, 3, 1, -4, ...
Each row obeys the same linear recurrence and is a version of the row 4 lines farther up in the same array shifted right by 12 places.

Programs

Formula

a(n) = Sum_{k=0..floor(n/2)} A192011(n-k,k).
a(n) = a(n-1) - a(n-4), n > 3.
From R. J. Mathar, Nov 02 2011: (Start)
G.f.: (-1 + 3*x) / (1 - x + x^4).
a(n) = 3*A099530(n-1) - A099530(n). (End)
Showing 1-4 of 4 results.