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 1-10 of 13 results. Next

A258172 Sum over all Dyck paths of semilength n of products over all peaks p of x_p, where x_p is the x-coordinate of peak p.

Original entry on oeis.org

1, 1, 5, 40, 434, 5901, 95997, 1812525, 38875265, 932135347, 24678938063, 714385754446, 22428656766320, 758632387171075, 27489135956517315, 1061913384743418360, 43550536908458238570, 1889211624465639489675, 86406059558668152123975, 4154647501527354507485040
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, x, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, x, 1] + b[x - 1, y + 1, True]]];
    a[n_] := b[2*n, 0, False];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258174 Sum over all Dyck paths of semilength n of products over all peaks p of x_p*y_p, where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 1, 7, 84, 1486, 35753, 1111931, 43150593, 2035666985, 114412223081, 7538224510181, 574552299138202, 50096579094908148, 4949493445607316419, 549534510282406667069, 68071071679372210762156, 9347203754680124767253730, 1414740620049957735248175695
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, x*y, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, x*y, 1] + b[x - 1, y + 1, True]]];
    a[n_] := b[2*n, 0, False];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258175 Sum over all Dyck paths of semilength n of products over all peaks p of x_p+y_p, where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 2, 12, 114, 1448, 22770, 424164, 9095450, 220023184, 5914998594, 174682531260, 5614908340866, 194967208057272, 7267467723747218, 289270983756577620, 12239218862861690250, 548301077168477951520, 25918121712918957399426, 1288797080051656060595820
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, x+y, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, x + y, 1] + b[x - 1, y + 1, True]]];
    a[n_] := b[2*n, 0, False];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258176 Sum over all Dyck paths of semilength n of products over all peaks p of x_p^y_p, where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 1, 7, 142, 9354, 2503597, 3260627607, 24105227716863, 1028836978599566213, 290383808553140390346475, 511963364817949502725911280781, 6704846980724405836568589845161191576, 584709361918378923208855262622537662297053728
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, x^y, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..15);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, x^y, 1] + b[x - 1, y + 1, True]]];
    a[n_] :=  b[2*n, 0, False];
    Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258177 Sum over all Dyck paths of semilength n of products over all peaks p of y_p^x_p, where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 1, 5, 112, 15312, 22928885, 475971133797, 164769697242392241, 1674694178196441599627207, 434453335415659344048321288040053, 2772047111897899211702422870954450438220795, 919691726760748842849028933552012720445531166591469510
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, y^x, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..15);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, y^x, 1] + b[x - 1, y + 1, True]]];
    a[n_] :=  b[2*n, 0, False];
    Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258178 Sum over all Dyck paths of semilength n of products over all peaks p of x_p^2, where x_p is the x-coordinate of peak p.

Original entry on oeis.org

1, 1, 13, 414, 24324, 2279209, 311524201, 58467947511, 14424374692879, 4525566110365523, 1759527523008436279, 830255082140922306224, 467382831980334193769718, 309419146352957449765072455, 237980526477430552734199922151, 210427994109788912088395561755374
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, x^2, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, x^2, 1] + b[x - 1, y + 1, True] ]];
    a[n_] :=  b[2*n, 0, False];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258179 Sum over all Dyck paths of semilength n of products over all peaks p of y_p^2, where y_p is the y-coordinate of peak p.

Original entry on oeis.org

1, 1, 5, 34, 312, 3649, 52161, 889843, 17796555, 411120395, 10838039407, 322752018060, 10762432731362, 398802951148255, 16312276452291935, 732189190349581890, 35876807697443520000, 1910107567584518883891, 110035833179472385285367, 6832792252684597270659486
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, y^2, 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..20);
  • Mathematica
    nmax = 20; Clear[g]; g[nmax+1] = 1; g[k_] := g[k] = 1 - x/( (k+2)^2*x - 1/g[k+1]); CoefficientList[Series[g[0], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 20 2015, after Sergei N. Gladkovskii *)

Formula

G.f.: T(0), where T(k) = 1 - x/( (k+2)^2*x - 1/T(k+1) ); (continued fraction). - Sergei N. Gladkovskii, Aug 20 2015

A258180 Sum over all Dyck paths of semilength n of products over all peaks p of C(x_p,y_p), where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 1, 4, 33, 517, 15326, 852912, 91023697, 19716262702, 8794395041567, 8016790849841585, 15556074485786226848, 64891787190080888991273, 561815453349204340865790817, 10402242033224422585780623039909, 423787530114579490372987256671625678
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, binomial(x, y), 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, Binomial[x, y], 1] + b[x - 1, y + 1, True]]];
    a[n_] := b[2*n, 0, False];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

A258181 Sum over all Dyck paths of semilength n of products over all peaks p of 2^(x_p-y_p), where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 1, 5, 89, 5933, 1540161, 1584150165, 6497470064169, 106497075348688637, 6980195689972655145233, 1829876050804408046228327525, 1918781572083632396857805205324025, 8047973452254281276702044410544321359565, 135022681866797995009325363468217320506328688097
Offset: 0

Views

Author

Alois P. Heinz, May 22 2015

Keywords

Comments

A Dyck path of semilength n is a (x,y)-lattice path from (0,0) to (2n,0) that does not go below the x-axis and consists of steps U=(1,1) and D=(1,-1). A peak of a Dyck path is any lattice point visited between two consecutive steps UD.

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false)*`if`(t, 2^(x-y), 1) +
                       b(x-1, y+1, true)  ))
        end:
    a:= n-> b(2*n, 0, false):
    seq(a(n), n=0..15);
  • Mathematica
    b[x_, y_, t_] := b[x, y, t] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False]*If[t, 2^(x - y), 1] + b[x - 1, y + 1, True]]];
    a[n_] := b[2*n, 0, False];
    Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

Formula

a(n) ~ c * 2^(n*(n-1)), where c = 1.47818066525747143617276638534... . - Vaclav Kotesovec, Jun 01 2015

A384613 Number of rooted ordered trees with n non-root nodes such that all leaf nodes can be k different colors where k is the degree of their parent node.

Original entry on oeis.org

1, 1, 5, 36, 340, 4019, 57696, 982146, 19419042, 438068191, 11106513798, 312555754796, 9663786464541, 325515760762637, 11861723942987878, 464834173383876612, 19490387161582849600, 870582781070074780946, 41266849779858887379029, 2068827708558025551348644
Offset: 0

Views

Author

John Tyler Rascoe, Jun 04 2025

Keywords

Examples

			a(2) = 5 counts:
   o      o        o        o        o
   |     / \      / \      / \      / \
   o   (1) (1)  (1) (2)  (2) (1)  (2) (2)
   |
  (1)
		

Crossrefs

Programs

  • PARI
    G(k,N) = if(k>N, 1, 1+ sum(i=1,N, (x*(G(k+1,N-i+1)+i-1))^i))
    G_x(N) = {my(x='x+O('x^N)); Vec(G(1,N)+ O('x^(N+1)))}

Formula

G.f.: G(x) satisfies G(x) = Sum_{i>=0} (x*(G(x) + i - 1))^i.
Showing 1-10 of 13 results. Next