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.

A258224 Row sums of A258223.

Original entry on oeis.org

1, 2, 13, 166, 3450, 105053, 4385297, 239389538, 16497800177, 1396841773631, 142194450687440, 17100401655609460, 2394468068218870494, 385647096554809325098, 70702689662684594772871, 14623755150209185924416598, 3385915623744083331349813602
Offset: 0

Views

Author

Alois P. Heinz, May 23 2015

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (k*x+y)/y, 1)
                     + b(x-1, y+1, true, k)  ))
        end:
    A:= (n, k)-> b(2*n, 0, false, k):
    T:= proc(n,k) option remember;
           add(A(n, i)*(-1)^(k-i)*binomial(k, i), i=0..k)/k!
        end:
    a:= proc(n) option remember; add(T(n,k), k=0..n) end:
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y > x || y < 0, 0,
         If[x == 0, 1, b[x - 1, y - 1, False, k]*If[t, (k*x + y)/y, 1]
                     + b[x - 1, y + 1, True, k]]];
    A[n_, k_] := b[2*n, 0, False, k];
    T[n_, k_] := Sum[A[n, i]*(-1)^(k - i)*Binomial[k, i], {i, 0, k}]/k!;
    a[n_] := Sum[T[n, k], {k, 0, n}];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 28 2022, after Alois P. Heinz *)

Formula

a(n) = Sum_{k=0..n} A258223(n,k).

A292695 a(n) = A258223(2n,n).

Original entry on oeis.org

1, 8, 1749, 1944225, 6439957299, 47971886252910, 677927299391810160, 16243385150174371081830, 609634394448842168438414483, 33797743985046745897969800271770, 2645657421035128682909045799293446355, 282144864134810484141733900449168244617439
Offset: 0

Views

Author

Alois P. Heinz, Sep 20 2017

Keywords

Crossrefs

Cf. A258223.

A258220 T(n,k) = 1/k! * Sum_{i=0..k} (-1)^(k-i) *C(k,i) * A258219(n,i); triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 4, 6, 1, 25, 49, 15, 1, 208, 498, 217, 28, 1, 2146, 6016, 3360, 635, 45, 1, 26368, 84042, 56728, 13997, 1475, 66, 1, 375733, 1332661, 1046619, 316281, 43974, 2954, 91, 1, 6092032, 23660034, 21053089, 7479444, 1283817, 114576, 5334, 120, 1
Offset: 0

Views

Author

Alois P. Heinz, May 23 2015

Keywords

Examples

			Triangle T(n,k) begins:
:     1;
:     1,     1;
:     4,     6,     1;
:    25,    49,    15,     1;
:   208,   498,   217,    28,    1;
:  2146,  6016,  3360,   635,   45,  1;
: 26368, 84042, 56728, 13997, 1475, 66, 1;
		

Crossrefs

Column k=0 gives A005411 (for n>0).
Main diagonal and lower diagonal give: A000012, A000384(n+1).
Row sums give A258221.
T(2n,n) gives A292692.

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (x+k*y)/y, 1)
                     + b(x-1, y+1, true, k)  ))
        end:
    A:= (n, k)-> b(2*n, 0, false, k):
    T:= (n, k)-> add(A(n, i)*(-1)^(k-i)*binomial(k, i), i=0..k)/k!:
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y>x || y<0, 0, If[x==0, 1, b[x-1, y - 1, False, k]*If[t, (x+k*y)/y, 1] + b[x-1, y+1, True, k]]]; A[n_, k_] := b[2*n, 0, False, k]; T [n_, k_] := Sum[A[n, i]*(-1)^(k-i)*Binomial[k, i], {i, 0, k}]/k!; Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Feb 20 2017, translated from Maple *)

Formula

T(n,k) = 1/k! * Sum_{i=0..k} (-1)^(k-i) *C(k,i) * A258219(n,i).

A258222 A(n,k) is the sum over all Dyck paths of semilength n of products over all peaks p of (k*x_p+y_p)/y_p, where x_p and y_p are the coordinates of peak p; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 10, 5, 1, 4, 24, 74, 14, 1, 5, 44, 297, 706, 42, 1, 6, 70, 764, 4896, 8162, 132, 1, 7, 102, 1565, 17924, 100278, 110410, 429, 1, 8, 140, 2790, 47650, 527844, 2450304, 1708394, 1430, 1, 9, 184, 4529, 104454, 1831250, 18685164, 69533397, 29752066, 4862
Offset: 0

Views

Author

Alois P. Heinz, May 23 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.

Examples

			Square array A(n,k) begins:
:  1,    1,      1,      1,       1,       1, ...
:  1,    2,      3,      4,       5,       6, ...
:  2,   10,     24,     44,      70,     102, ...
:  5,   74,    297,    764,    1565,    2790, ...
: 14,  706,   4896,  17924,   47650,  104454, ...
: 42, 8162, 100278, 527844, 1831250, 4953222, ...
		

Crossrefs

Columns k=0-1 give: A000108, A000698(n+1).
Rows n=0-2 give: A000012, A000027(k+1), A049450(k+1).
Main diagonal gives A292694.

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (k*x+y)/y, 1)
                     + b(x-1, y+1, true, k)  ))
        end:
    A:= (n, k)-> b(2*n, 0, false, k):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False, k]*If[t, (k*x + y)/y, 1] + b[x - 1, y + 1, True, k]]];
    A [n_, k_] := b[2*n, 0, False, k];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Apr 23 2016, translated from Maple *)

Formula

A(n,k) = Sum_{i=0..min(n,k)} C(k,i) * i! * A258223(n,i).
Showing 1-4 of 4 results.