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.

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A187084 Exponential Riordan array (1,4*x+6*x^2+4*x^3+x^4).

Original entry on oeis.org

4, 12, 16, 24, 144, 64, 24, 816, 1152, 256, 0, 3360, 12480, 7680, 1024, 0, 10080, 100800, 134400, 46080, 4096, 0, 20160, 645120, 1747200, 1182720, 258048, 16384, 0, 20160, 3306240, 18305280, 22364160, 9117696, 1376256, 65536, 0, 0, 13305600, 159667200, 341591040, 235339776, 63995904, 7077888, 262144
Offset: 1

Views

Author

Vladimir Kruchinin, Mar 04 2011

Keywords

Comments

The column of index 0 contains a 1 followed by zeros and is not incorporated here.
Also the Bell polynomials of the second kind B(n,k)(4,12,24,24).
If the argument vector is generalized to contain falling powers of a variable x, B(n,k)(4*x^3,12*x,24*x,24) =sum_{j=0..k} binomial(k,j) *sum_{i=j..n-k+j} 6^(i-j) *binomial(j,i-j) *binomial(k-j,n-3*k+3*j-i) *4^(4*k-n-2*j) *x^(4*k-n) *n!/k!.

Examples

			Triangle begins:
  4;
  12,16;
  24,144,64;
  24,816,1152,256;
  0,3360,12480,7680,1024;
  0,10080,100800,134400,46080,4096;
  0,20160,645120,1747200,1182720,258048,16384;
  0,20160,3306240,18305280,22364160,9117696,1376256,65536;
  ...
		

Crossrefs

Cf. A008279 (its row 4), A188138, A188062, A188066.

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    # Adds (1,0,0,0, ..) as column 0.
    BellMatrix(n -> `if`(n<4,[4,12,24,24][n+1],0), 9); # Peter Luschny, Jan 29 2016
  • Mathematica
    BellMatrix[f_, len_] := With[{t = Array[f, len, 0]}, Table[BellY[n, k, t], {n, 0, len - 1}, {k, 0, len - 1}]];
    B = BellMatrix[Function[n, If[n<4, {4, 12, 24, 24}[[n+1]], 0]], rows = 12];
    Table[B[[n, k]], {n, 2, rows}, {k, 2, n}] // Flatten (* Jean-François Alcover, Jun 28 2018, after Peter Luschny *)
  • Maxima
    B(n,k):=n!/k!*sum(binomial(k,j)*sum(6^(i-j)*binomial(j,i-j)*binomial(k-j,n-3*k+3*j-i),i,j,n-k+j)*4^(4*k-n-2*j),j,0,k);

Formula

B(n,k) = (n!/k!)*Sum_{j=0..k} binomial(k,j)*( Sum_{i=j..n-k+j} 6^(i-j)*binomial(j,i-j)*binomial(k-j,n-3*k+3*j-i) )*4^(4*k-n-2*j).
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