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.

Previous Showing 21-27 of 27 results.

A191649 Number of lattice paths from (0,0) to (n,n) using steps (0,1), (1,0), (1,1), (2,2).

Original entry on oeis.org

1, 3, 14, 71, 379, 2082, 11651, 66051, 378064, 2180037, 12644861, 73695358, 431209313, 2531556197, 14904832196, 87970766447, 520337606401, 3083584244460, 18304476242735, 108820740004749, 647817646760368, 3861215365595659, 23039691494489015, 137615812845579390
Offset: 0

Views

Author

Joerg Arndt, Jun 30 2011

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( 1/Sqrt(x^4+2*x^3-x^2-6*x+1) )); // G. C. Greubel, Apr 29 2019
    
  • Mathematica
    CoefficientList[Series[1/Sqrt[x^4 + 2 x^3 - x^2 - 6 x + 1], {x, 0, 23}], x] (* Michael De Vlieger, Oct 08 2016 *)
  • PARI
    /* same as in A092566 but use */
    steps=[[0,1], [1,0], [1,1], [2,2]];
    /* Joerg Arndt, Jun 30 2011 */
    
  • PARI
    my(x='x+O('x^30)); Vec(1/sqrt(x^4+2*x^3-x^2-6*x+1)) \\ G. C. Greubel, Apr 29 2019
    
  • Sage
    (1/sqrt(x^4+2*x^3-x^2-6*x+1)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Apr 29 2019

Formula

G.f.: 1/sqrt(x^4 +2*x^3 -x^2 -6*x +1). - Mark van Hoeij, Apr 17 2013
D-finite with recurrence: n*a(n) +3*(-2*n+1)*a(n-1) +(-n+1)*a(n-2) +(2*n-3)*a(n-3) +(n-2)*a(n-4)=0. - R. J. Mathar, Oct 08 2016

A192371 Number of lattice paths from (0,0) to (n,n) using steps (1,1), (0,2), (2,0), (0,3), (3,0).

Original entry on oeis.org

1, 1, 3, 9, 25, 87, 307, 1113, 4149, 15605, 59201, 225999, 866449, 3333847, 12865335, 49769689, 192945411, 749396493, 2915432049, 11358771965, 44313108627, 173081422997, 676766482917, 2648843996031, 10376891445525, 40685535827325, 159641884780749, 626849029013919, 2463010645910537, 9683604464279235
Offset: 0

Views

Author

Joerg Arndt, Jul 01 2011

Keywords

Crossrefs

Programs

  • Maple
    s := RootOf( (s^3-s-1)*(s-1)+x*s*(4-3*s), s);
    ogf := sqrt(4*s-3*s^2)*(s^3-4*s^2+2*s+2)/((2*s^2-s-2)*(3*s^3-6*s^2+4*s-2)*(1-x)):
    series(ogf, x=0, 30);  # Mark van Hoeij, Apr 17 2013
    # second Maple program:
    b:= proc(p) b(p):= `if`(p=[0$2], 1, `if`(min(p[])<0, 0,
          add(b(p-l), l=[[1, 1], [0, 2], [2, 0], [0, 3], [3, 0]])))
        end:
    a:= n-> b([n$2]):
    seq(a(n), n=0..30);  # Alois P. Heinz, Aug 18 2014
  • Mathematica
    b[p_List] := b[p] = If[p == {0, 0}, 1, If[Min[p] < 0, 0, Sum[b[p - l], {l, {{1, 1}, {0, 2}, {2, 0}, {3, 0}, {0, 3}}}]]]; a[n_] := b[{n, n}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, May 27 2015, after Alois P. Heinz *)
  • PARI
    /* same as in A092566 but use */
    steps=[[1,1], [2,0], [0,2], [3,0], [0,3]];
    /* Joerg Arndt, Jun 30 2011 */

Formula

G.f.: sqrt(4*s-3*s^2)*(s^3-4*s^2+2*s+2)/((2*s^2-s-2)*(3*s^3-6*s^2+4*s-2)*(1-x)) where the function s satisfies (s^3-s-1)*(s-1)+x*s*(4-3*s) = 0. - Mark van Hoeij, Apr 17 2013

A192417 Number of lattice paths from (0,0) to (n,n) using steps (0,1), (1,0), (2,2), (3,3).

Original entry on oeis.org

1, 2, 7, 27, 107, 436, 1810, 7609, 32288, 138009, 593311, 2562725, 11112720, 48347332, 210936119, 922550622, 4043488129, 17755735241, 78099099877, 344033901804, 1517535718392, 6701979806379, 29630948706756, 131136723532257, 580901892464599, 2575423975663301
Offset: 0

Views

Author

Joerg Arndt, Jun 30 2011

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( 1/Sqrt(x^6+2*x^5+x^4-2*x^3-2*x^2-4*x+1) )); // G. C. Greubel, Apr 29 2019
    
  • Mathematica
    CoefficientList[Series[1/Sqrt[x^6+2x^5+x^4-2x^3-2x^2-4x+1], {x, 0, 25}], x] (* Michael De Vlieger, Oct 08 2016 *)
  • PARI
    /* same as in A092566 but use */
    steps=[[0,1], [1,0], [2,2], [3,3]];
    /* Joerg Arndt, Jun 30 2011 */
    
  • PARI
    my(x='x+O('x^30)); Vec(1/sqrt(x^6+2*x^5+x^4-2*x^3-2*x^2-4*x+1)) \\ G. C. Greubel, Apr 29 2019
    
  • Sage
    (1/sqrt(x^6+2*x^5+x^4-2*x^3-2*x^2-4*x+1)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Apr 29 2019

Formula

G.f.: 1/sqrt(x^6+2*x^5+x^4-2*x^3-2*x^2-4*x+1). - Mark van Hoeij, Apr 17 2013
D-finite with recurrence: n*a(n) +2*(-2*n+1)*a(n-1) +2*(-n+1)*a(n-2) +(-2*n+3)*a(n-3) +(n-2)*a(n-4) +(2*n-5)*a(n-5) +(n-3)*a(n-6)=0. - R. J. Mathar, Oct 08 2016

A192446 Number of lattice paths from (0,0) to (n,n) using steps (1,0), (3,0), (0,1), (0,3).

Original entry on oeis.org

1, 2, 6, 30, 154, 768, 3906, 20232, 105750, 556328, 2943432, 15646932, 83500126, 447057380, 2400249624, 12918250836, 69674241654, 376489511460, 2037768450480, 11045915485740, 59955446568276, 325821729044784, 1772588671356204, 9653187691115640, 52617711157401186, 287051310425050668
Offset: 0

Views

Author

Joerg Arndt, Jul 01 2011

Keywords

Comments

Diagonal of rational function 1/(1 - (x + y + x^3 + y^3)). - Gheorghe Coserea, Aug 06 2018

Crossrefs

Programs

  • Maple
    REL := 3*s^2*x^2-(1-2*s^2+2*s^3)*x-s*(s^3+2*s^2+s-1);
    ogf := sqrt((8*s^2*(x*(1-8*s^2-4*s^3)-2*s^4-4*s^3-8*s^2+2*s+3)/3-1)/(4*x^3+8*x^2+4*x-1))/(1-4*s^3);
    series(eval(ogf, s=RootOf(REL,s)),x=0,30);  # Mark van Hoeij, Apr 17 2013
    # second Maple program:
    b:= proc(x, y) option remember; `if`(y=0, 1, add((p->
          `if`(p[1]<0, 0, b(p[1], p[2])))(sort([x, y]-h)),
            h=[[1, 0], [0, 1], [3, 0], [0, 3]]))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);  # Alois P. Heinz, Dec 28 2018
  • Mathematica
    a[0, 0] = 1; a[n_, k_] /; n >= 0 && k >= 0 := a[n, k] = a[n, k-1] + a[n, k-3] + a[n-1, k] + a[n-3, k]; a[, ] = 0;
    a[n_] := a[n, n];
    a /@ Range[0, 30] (* Jean-François Alcover, Oct 06 2019 *)
  • PARI
    /* same as in A092566 but use */
    steps=[[1,0], [3,0], [0,1], [0,3]];
    /* Joerg Arndt, Jun 30 2011 */
    
  • PARI
    seq(N) = {
      my(x='x + O('x^N), d=16*x^6 + 16*x^5 + 16*x^4 - 8*x^3 - 4*x^2 + 1,
         s=serreverse((1 - 2*x^2 + 2*x^3 - sqrt(d))/(6*x^2)));
      Vec(sqrt((8*s^2*(x*(1-8*s^2-4*s^3)-2*s^4-4*s^3-8*s^2+2*s+3)/3-1)/(4*x^3+8*x^2+4*x-1))/(1-4*s^3));
    };
    seq(26) \\ Gheorghe Coserea, Aug 06 2018

Formula

G.f.: sqrt((8*s^2*(x*(1-8*s^2-4*s^3)-2*s^4-4*s^3-8*s^2+2*s+3)/3-1)/(4*x^3+8*x^2+4*x-1))/(1-4*s^3) where s is a function satisfying 3*s^2*x^2-(1-2*s^2+2*s^3)*x-s*(s^3+2*s^2+s-1)=0. - Mark van Hoeij, Apr 17 2013
From Gheorghe Coserea, Aug 06 2018: (Start)
G.f. y=A(x) satisfies:
0 = (4*x^3 + 8*x^2 + 4*x - 1)^4*(108*x^3 - 108*x^2 + 36*x - 31)^2*y^8 + 4*(4*x^3 + 8*x^2 + 4*x - 1)^3*(36*x^3 + 36*x^2 - 4*x - 13)*(108*x^3 - 108*x^2 + 36*x - 31)*y^6 + 2*(4*x^3 + 8*x^2 + 4*x - 1)^2*(2160*x^6 + 4320*x^5 + 1872*x^4 - 1784*x^3 - 1576*x^2 + 472*x + 431)*y^4 + 4*(4*x^3 + 8*x^2 + 4*x - 1)*(112*x^6 + 448*x^5 + 688*x^4 + 456*x^3 + 96*x^2 + 40*x + 55)*y^2 + (4*x^3 + 12*x^2 + 12*x + 3)^2.
0 = (4*x^3 + 8*x^2 + 4*x - 1)*(108*x^3 - 108*x^2 + 36*x - 31)*(270*x^4 + 180*x^3 + 144*x^2 - 225*x - 59)*y''' + (1283040*x^9 + 1924560*x^8 + 1080864*x^7 - 1425816*x^6 - 2135376*x^5 + 33048*x^4 + 702468*x^3 + 134520*x^2 + 43892*x + 30575)*y'' + 30*(111780*x^8 + 149040*x^7 + 120960*x^6 - 122094*x^5 - 172206*x^4 - 6012*x^3 + 36615*x^2 + 10298*x - 1541)*y' + 60*(29160*x^7 + 34020*x^6 + 36288*x^5 - 43092*x^4 - 45882*x^3 - 6462*x^2 + 1890*x + 913)*y.
(End)

A261507 Fibonacci-numbered rows of Pascal's triangle. Triangle read by rows: T(n,k)= binomial(Fibonacci(n), k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 5, 10, 10, 5, 1, 1, 8, 28, 56, 70, 56, 28, 8, 1, 1, 13, 78, 286, 715, 1287, 1716, 1716, 1287, 715, 286, 78, 13, 1, 1, 21, 210, 1330, 5985, 20349, 54264, 116280, 203490, 293930, 352716, 352716, 293930, 203490, 116280, 54264, 20349, 5985, 1330, 210, 21, 1
Offset: 0

Views

Author

Maghraoui Abdelkader, Aug 22 2015

Keywords

Comments

Subsequence of A007318.

Examples

			1,
1,  1,
1,  1,
1,  2,  1,
1,  3,  3,   1,
1,  5, 10,  10,   5,    1,
1,  8, 28,  56,  70,   56,   28,    8,    1,
1, 13, 78, 286, 715, 1287, 1716, 1716, 1287, 715, 286, 78, 13, 1
		

Crossrefs

Programs

  • Mathematica
    Table[Binomial[Fibonacci[n], k], {n, 0, 8}, {k, 0, Fibonacci[n]}]//Flatten (* Jean-François Alcover, Nov 12 2015*)
  • PARI
    v = vector(101,j,fibonacci(j)); i=0; n=0; while(n<100, for(k=0, n, print1(binomial(n, k), ", ","")); print(); i=i+1; n=v[i] ;)

Formula

T(n, k) = binomial(fibonacci(n), k).
T(n, 1) = fibonacci(n) = A000045(n).
T(n, 2) = A191797(n) for n>3.

A383474 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where A(n,k) is the number of lattice paths from (0,0) to (n,k) using steps (1,0),(2,0),(3,0),(0,1),(0,2),(0,3).

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 4, 5, 5, 4, 7, 12, 14, 12, 7, 13, 26, 37, 37, 26, 13, 24, 56, 89, 106, 89, 56, 24, 44, 118, 209, 277, 277, 209, 118, 44, 81, 244, 477, 698, 784, 698, 477, 244, 81, 149, 499, 1063, 1700, 2113, 2113, 1700, 1063, 499, 149, 274, 1010, 2329, 4026, 5469, 6040, 5469, 4026, 2329, 1010, 274
Offset: 0

Views

Author

Seiichi Manyama, Apr 27 2025

Keywords

Examples

			Square array A(n,k) begins:
   1,   1,   2,    4,    7,    13,    24, ...
   1,   2,   5,   12,   26,    56,   118, ...
   2,   5,  14,   37,   89,   209,   477, ...
   4,  12,  37,  106,  277,   698,  1700, ...
   7,  26,  89,  277,  784,  2113,  5469, ...
  13,  56, 209,  698, 2113,  6040, 16497, ...
  24, 118, 477, 1700, 5469, 16497, 47332, ...
		

Crossrefs

Column k=0..1 give A000073(n+2), A073778(n+4).
Main diagonal gives A122680.

Programs

  • PARI
    a(n, k) = my(x='x+O('x^(n+1)), y='y+O('y^(k+1))); polcoef(polcoef(1/(1-x-y-x^2-y^2-x^3-y^3), n), k);

Formula

A(n,k) = A(k,n).
A(n,k) = A(n-1,k) + A(n-2,k) + A(n-3,k) + A(n,k-1) + A(n,k-2) + A(n,k-3).
G.f.: 1 / (1 - x - y - x^2 - y^2 - x^3 - y^3).

A191678 Number of lattice paths from (0,0) to (n,n) using steps (1,0), (1,1), (0,2), (2,2).

Original entry on oeis.org

1, 1, 5, 15, 62, 233, 937, 3729, 15121, 61492, 251942, 1036215, 4279754, 17731181, 73670725, 306823695, 1280574706, 5354602495, 22426876445, 94070238840, 395106054632, 1661489413472, 6994494531010, 29474635716345, 124319047552309, 524797934104312, 2217091297558466, 9373180869094923
Offset: 0

Views

Author

Joerg Arndt, Jun 30 2011

Keywords

Crossrefs

Programs

  • Maple
    P := (4*x^6+12*x^5-20*x^3+27*x^2+12*x-4)*A^3-(3*x^2+3*x-3)*A+1;
    Q := eval(P, A=A+1):
    series(RootOf(Q,A)+1, x=0, 30);  # Mark van Hoeij, Apr 17 2013
  • PARI
    /* same as in A092566 but use */
    steps=[[1,0], [1,1], [0,2], [2,2]];
    /* Joerg Arndt, Jun 30 2011 */

Formula

G.f.: A(x) where (4*x^6+12*x^5-20*x^3+27*x^2+12*x-4)*A(x)^3-(3*x^2+3*x-3)*A(x)+1 = 0. - Mark van Hoeij, Apr 17 2013
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