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.

A316101 Sequence a_k of column k shifts left when Weigh transform is applied k times with a_k(n) = n for n<2; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 0, 1, 1, 1, 3, 3, 1, 0, 1, 1, 1, 4, 6, 6, 1, 0, 1, 1, 1, 5, 10, 16, 12, 1, 0, 1, 1, 1, 6, 15, 32, 43, 25, 1, 0, 1, 1, 1, 7, 21, 55, 105, 120, 52, 1, 0, 1, 1, 1, 8, 28, 86, 210, 356, 339, 113, 1, 0, 1, 1, 1, 9, 36, 126, 371, 826, 1227, 985, 247, 1
Offset: 0

Views

Author

Alois P. Heinz, Jun 24 2018

Keywords

Examples

			Square array A(n,k) begins:
  0,  0,   0,   0,   0,    0,    0,    0,    0, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  2,   3,   4,   5,    6,    7,    8,    9, ...
  1,  3,   6,  10,  15,   21,   28,   36,   45, ...
  1,  6,  16,  32,  55,   86,  126,  176,  237, ...
  1, 12,  43, 105, 210,  371,  602,  918, 1335, ...
  1, 25, 120, 356, 826, 1647, 2961, 4936, 7767, ...
		

Crossrefs

Rows include (offsets may differ): A000004, A000012, A000027, A000217, A134465.
Main diagonal gives A316102.

Programs

  • Maple
    wtr:= proc(p) local b; b:= proc(n, i) option remember;
           `if`(n=0, 1, `if`(i<1, 0, add(binomial(p(i), j)*
             b(n-i*j, i-1), j=0..n/i))) end: j-> b(j$2)
          end:
    g:= proc(k) option remember; local b, t; b[0]:= j->
         `if`(j<2, j, b[k](j-1)); for t to k do
           b[t]:= wtr(b[t-1]) od: eval(b[0])
        end:
    A:= (n, k)-> g(k)(n):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    wtr[p_] := Module[{b}, b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[p[i], j]*b[n - i*j, i - 1], {j, 0, n/i}]]]; b[#, #]&];
    g[k_] := g[k] = Module[{b, t}, b[0][j_] := If[j < 2, j, b[k][j - 1]]; For[ t = 1, t <= k + 1, t++, b[t] = wtr[b[t - 1]]]; b[0]];
    A[n_, k_] := g[k][n];
    Table[A[n, d-n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Jul 10 2018, after Alois P. Heinz *)

A134464 (A127648 * A000012 + A000012 * A127773) - A000012.

Original entry on oeis.org

1, 2, 4, 3, 5, 8, 4, 6, 9, 13, 5, 7, 10, 14, 19, 6, 8, 11, 15, 20, 26, 7, 9, 12, 16, 21, 27, 34, 8, 10, 13, 17, 22, 28, 35, 43, 9, 11, 14, 18, 23, 29, 36, 44, 53, 10, 12, 15, 19, 24, 30, 37, 45, 54, 64
Offset: 1

Views

Author

Gary W. Adamson, Oct 26 2007

Keywords

Comments

Row sums = A134465: (1, 6, 16, 32, 55, 86, ...).

Examples

			First few rows of the triangle:
  1;
  2,  4;
  3,  5,  8;
  4,  6,  9, 13;
  5,  7, 10, 14, 19;
  6,  8, 11, 15, 20, 26;
  7,  9, 12, 16, 21, 27, 34;
  ...
		

Crossrefs

Programs

  • Mathematica
    Flatten[Table[RecurrenceTable[{a[1]==i,a[n]==a[n-1]+n},a,{n,i}],{i,10}]] (* Harvey P. Dale, Nov 12 2013 *)

Formula

(A127648 * A000012 * A000012 * A127773) - A000012, as infinite lower triangular matrices.

A135855 A007318 * a tridiagonal matrix with (1, 4, 1, 0, 0, 0, ...) in every column.

Original entry on oeis.org

1, 5, 1, 10, 6, 1, 16, 16, 7, 1, 23, 32, 23, 8, 1, 31, 55, 55, 31, 9, 1, 40, 86, 110, 86, 40, 10, 1, 50, 126, 196, 196, 126, 50, 11, 1, 61, 176, 322, 392, 322, 176, 61, 12, 1, 73, 237, 498, 714, 714, 498, 237, 73, 13, 1
Offset: 0

Views

Author

Gary W. Adamson, Dec 01 2007

Keywords

Examples

			First few rows of the triangle:
   1;
   5,  1;
  10,  6,   1;
  16, 16,   7,  1;
  23, 32,  23,  8,  1;
  31, 55,  55, 31,  9,  1;
  40, 86, 110, 86, 40, 10, 1;
  ...
		

Crossrefs

Programs

  • Magma
    A135855:= func< n,k | Binomial(n,k)*(n^2 + (2*k+7)*n - 2*(k^2 + 2*k -1))/((k+1)*(k+2)) >;
    [A135855(n,k): k in [0..n], n in [0..10]]; // G. C. Greubel, Feb 06 2022
    
  • Mathematica
    T[n_, k_]:= T[n, k]= If[k<0 || k>n, 0, If[k==0, (n^2+7*n+2)/2, If[k==n, 1, T[n-1, k-1] + T[n-1, k]]]];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Feb 06 2022 *)
  • Sage
    @CachedFunction
    def T(n,k): # A135855
        if (k==0): return (n^2+7*n+2)/2
        elif (k==n): return 1
        else: return T(n-1, k-1) + T(n-1, k)
    flatten([[T(n,k) for k in (0..n)] for n in (0..10)]) # G. C. Greubel, Feb 06 2022

Formula

Binomial transform of an infinite tridiagonal matrix with (1, 4, 1, 0, 0, 0, ...) in every column; i.e., (1, 1, 1, ...) in the main diagonal, (4, 4, 4, 0, 0, 0, ...) in the subdiagonal and (1, 1, 1, ...) in the subsubdiagonal.
T(n, 0) = A052905(n).
Sum_{k=0..n} T(n, k) = A101945(n).
From G. C. Greubel, Feb 06 2022: (Start)
T(n, k) = T(n-1, k-1) + T(n-1, k), with T(n, n) = 1, T(n, 0) = A052905(n).
T(n, k) = binomial(n,k)*(n^2 + (2*k+7)*n - 2*(k^2 + 2*k -1))/((k+1)*(k+2)).
T(n, 1) = A134465(n).
T(n, 2) = A022815(n-1).
T(n, n-1) = n+3.
T(n, n-2) = A052905(n+2). (End)
Showing 1-3 of 3 results.