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 1-3 of 3 results.

A228334 Triangle read by rows: the X-transformation of the Catalan triangle A033184.

Original entry on oeis.org

1, 0, 1, 0, 3, 1, 0, 14, 10, 1, 0, 84, 90, 21, 1, 0, 594, 825, 308, 36, 1, 0, 4719, 7865, 4004, 780, 55, 1, 0, 40898, 78078, 49686, 13650, 1650, 78, 1, 0, 379236, 804440, 606424, 214200, 37400, 3094, 105, 1, 0, 3711916, 8565960, 7379904, 3162816, 724812, 88179, 5320, 136, 1
Offset: 0

Views

Author

N. J. A. Sloane, Aug 26 2013

Keywords

Examples

			Triangle begins:
  1;
  0,   1;
  0,   3,   1;
  0,  14,  10,   1;
  0,  84,  90,  21,   1;
  0, 594, 825, 308,  36,   1;
  ...
		

Crossrefs

Programs

  • Mathematica
    nn = 9;
    c[n_, k_] := Binomial[2n-k, n] (k+1)/(n+1);
    a[0, 0] = 1;
    a[n_, k_] := Table[c[n+k+i-1, 2k+j-1], {i, 1, 2}, {j, 1, 2}] // Det;
    Table[a[n, k], {n, 0, nn}, {k, 0, n}] // Flatten (* Jean-François Alcover, Aug 12 2018 *)
  • PARI
    C(n, k) = (k<=n)*binomial(2*n-k, n)*(k+1)/(n+1);
    aX(nn) = {for (n = 0, nn, for (k = 0, n, print1(matdet(matrix(2, 2, i, j, C(n+k+i-1, 2*k+j-1))), ", ");); print(););} \\ Michel Marcus, Feb 13 2014

Extensions

More terms from Michel Marcus, Feb 13 2014
A-number for Catalan triangle changed by Michel Marcus, Feb 13 2014

A228336 Triangle read by rows: the Z-transformation of the Catalan triangle A033184.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 4, 6, 3, 1, 10, 15, 12, 4, 1, 25, 45, 36, 20, 5, 1, 70, 126, 126, 70, 30, 6, 1, 196, 392, 392, 280, 120, 42, 7, 1, 588, 1176, 1344, 960, 540, 189, 56, 8, 1, 1764, 3780, 4320, 3600, 2025, 945, 280, 72, 9, 1, 5544, 11880, 14850, 12375, 8250, 3850, 1540, 396, 90, 10, 1
Offset: 0

Views

Author

N. J. A. Sloane, Aug 26 2013

Keywords

Examples

			Triangle begins:
   1;
   1,   1;
   2,   2,   1;
   4,   6,   3,  1;
  10,  15,  12,  4,  1;
  25,  45,  36, 20,  5, 1;
  70, 126, 126, 70, 30, 6, 1;
  ...
		

Crossrefs

Programs

  • Mathematica
    c[n_, k_] := Boole[k <= n] Binomial[2n - k, n] (k + 1)/(n + 1);
    T[n_, k_] := Module[{nn, kk}, If[OddQ[n], nn = (n + 1)/2, nn = n/2]; If[OddQ[k], kk = (k - 1)/2, kk = k/2]; If [OddQ[n], If[OddQ[k], c[nn + kk, 2kk + 1] c[nn + kk + 1, 2kk + 2], c[nn + kk, 2kk] c[nn + kk, 2kk + 1]], If[OddQ[k], c[nn + kk + 1, 2kk + 1] c[nn + kk + 1, 2kk + 2], c[nn + kk, 2kk] c[nn + kk + 1, 2kk + 1]]]];
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Oct 04 2018, from PARI *)
  • PARI
    C(n, k) = (k<=n)*binomial(2*n-k, n)*(k+1)/(n+1);
    T(n, k) = {my(nn, kk); if (n % 2, nn = (n+1)/2, nn = n/2); if (k % 2, kk = (k-1)/2, kk = k/2); if ((n % 2), if (k % 2, C(nn+kk, 2*kk+1)*C(nn+kk+1, 2*kk+2), C(nn+kk, 2*kk)*C(nn+kk, 2*kk+1)), if (k % 2, C(nn+kk+1, 2*kk+1)*C(nn+kk+1, 2*kk+2), C(nn+kk, 2*kk)*C(nn+kk+1, 2*kk+1)));} \\ Michel Marcus, Feb 13 2014

Extensions

More terms from Michel Marcus, Feb 13 2014
A-number for Catalan triangle changed by Michel Marcus, Feb 13 2014

A228337 Irregular triangle read by rows: the W-transformation of the Catalan triangle A033184.

Original entry on oeis.org

1, 2, 4, 1, 10, 4, 20, 21, 1, 56, 70, 6, 140, 238, 50, 1, 420, 792, 210, 8, 1176, 2604, 990, 91, 1, 3696, 8778, 3850, 462, 10, 11088, 29106, 15675, 2772, 144, 1, 36036, 99528, 59202, 12376, 858, 12, 113256, 335049, 228085, 60060, 6240, 209, 1
Offset: 0

Views

Author

N. J. A. Sloane, Aug 26 2013

Keywords

Examples

			Triangle begins:
     1;
     2;
     4,    1;
    10,    4;
    20,   21,    1;
    56,   70,    6;
   140,  238,   50,    1;
   420,  792,  210,    8;
  1176, 2604,  990,   91,    1;
  ...
		

Crossrefs

Programs

  • Mathematica
    nn = 12;
    c[n_, k_] := If[k <= n, Binomial[2n-k, n] (k+1)/(n+1), 0];
    a[n_, k_] := Table[c[If[OddQ[n], (n-1)/2+k+2i-2, n/2+k+i-1], 2k+j-1], {i, 1, 2}, {j, 1, 2}] // Permanent;
    Table[a[n, k], {n, 0, nn}, {k, 0, n/2}] // Flatten (* Jean-François Alcover, Aug 12 2018 *)
  • PARI
    C(n, k) = (k<=n)*binomial(2*n-k, n)*(k+1)/(n+1);
    matperm(M)=my(n=#M,t);sum(i=1,n!,t=numtoperm(n,i);prod(j=1,n,M[j,t[j]])); \\ from Rosetta code
    W(n, k) = my(nn); if (n % 2, nn = (n-1)/2; matperm(matrix(2, 2, i, j, C(nn+k+2*i-2, 2*k+j-1))), nn = n/2; matperm(matrix(2, 2, i, j, C(nn+k+i-1, 2*k+j-1))));
    aW(nn) = {for (n=0, nn, for (k=0, n\2, print1(W(n, k), ", ");); print(););} \\ Michel Marcus, Feb 13 2014

Extensions

More terms from Michel Marcus, Feb 13 2014
A-number for Catalan triangle changed by Michel Marcus, Feb 13 2014
Showing 1-3 of 3 results.