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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A144303 Square array A(n,m), n>=0, m>=0, read by antidiagonals: A(n,m) = n-th number of the m-th iteration of the hyperbinomial transform on the sequence of 1's.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 6, 1, 1, 4, 13, 29, 1, 1, 5, 22, 81, 212, 1, 1, 6, 33, 163, 689, 2117, 1, 1, 7, 46, 281, 1564, 7553, 26830, 1, 1, 8, 61, 441, 2993, 18679, 101961, 412015, 1, 1, 9, 78, 649, 5156, 38705, 268714, 1639529, 7433032, 1, 1, 10, 97, 911, 8257, 71801, 592489, 4538209, 30640257, 154076201, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 17 2008, revised Oct 30 2012

Keywords

Comments

See A088956 for the definition of the hyperbinomial transform.
A(n,m), n>=0, m>=0, is the number of subtrees of the complete graph K_{n+m} on n+m vertices containing a given, fixed subtree on m vertices. - Alex Chin, Jul 25 2013

Examples

			Square array begins:
  1,     1,      1,      1,      1,       1,       1, ...
  1,     2,      3,      4,      5,       6,       7, ...
  1,     6,     13,     22,     33,      46,      61, ...
  1,    29,     81,    163,    281,     441,     649, ...
  1,   212,    689,   1564,   2993,    5156,    8257, ...
  1,  2117,   7553,  18679,  38705,   71801,  123217, ...
  1, 26830, 101961, 268714, 592489, 1166886, 2120545, ...
		

Crossrefs

Rows n=0-2 give: A000012, A000027, A028872.
Main diagonal gives A252766.

Programs

  • Maple
    hymtr:= proc(p) proc(n,m) `if`(m=0, p(n), m*add(
               p(k)*binomial(n, k) *(n-k+m)^(n-k-1), k=0..n))
            end end:
    A:= hymtr(1):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    a[, 0] = 1; a[n, k_] := Sum[k*(n - j + k)^(n - j - 1)*Binomial[n, j], {j, 0, n}]; Table[a[n - k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Jun 24 2013 *)

Formula

E.g.f. of column k: exp(x) * (-LambertW(-x)/x)^k.
A(n,k) = Sum_{j=0..n} k * (n-j+k)^(n-j-1) * C(n,j).

A218501 9th iteration of the hyperbinomial transform on the sequence of 1's.

Original entry on oeis.org

1, 10, 118, 1621, 25588, 458605, 9232894, 206835751, 5113191304, 138473150833, 4081818946330, 130223467785619, 4473867764956204, 164772507070721989, 6479598382677480286, 271083794667222927655, 12026359894442420178064, 564099525344446492486105
Offset: 0

Views

Author

Alois P. Heinz, Oct 30 2012

Keywords

Comments

See A088956 for the definition of the hyperbinomial transform.

Crossrefs

Column k=9 of A144303.

Programs

  • Maple
    a:= n-> add(9*(n-j+9)^(n-j-1)*binomial(n,j), j=0..n):
    seq (a(n), n=0..20);
  • Mathematica
    Table[Sum[9*(n-j+9)^(n-j-1)*Binomial[n,j],{j,0,n}],{n,0,20}] (* Vaclav Kotesovec, Oct 18 2013 *)

Formula

E.g.f.: exp(x) * (-LambertW(-x)/x)^9.
a(n) = Sum_{j=0..n} 9 * (n-j+9)^(n-j-1) * C(n,j).
Hyperbinomial transform of A218500.
a(n) ~ 9*exp(9+exp(-1))*n^(n-1). - Vaclav Kotesovec, Oct 18 2013
Showing 1-2 of 2 results.