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.

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).

A089463 Triangle, read by rows, of coefficients for the third iteration of the hyperbinomial transform.

Original entry on oeis.org

1, 3, 1, 15, 6, 1, 108, 45, 9, 1, 1029, 432, 90, 12, 1, 12288, 5145, 1080, 150, 15, 1, 177147, 73728, 15435, 2160, 225, 18, 1, 3000000, 1240029, 258048, 36015, 3780, 315, 21, 1, 58461513, 24000000, 4960116, 688128, 72030, 6048, 420, 24, 1, 1289945088
Offset: 0

Views

Author

Paul D. Hanna, Nov 05 2003

Keywords

Comments

Equals the matrix cube of A088956 when treated as a lower triangular matrix. The 3rd hyperbinomial transform of a sequence {b} is defined to be the sequence {d} given by d(n) = Sum_{k=0..n} T(n,k)*b(k), where T(n,k) = 3*(n-k+3)^(n-k-1)*C(n,k). Given a table in which the n-th row is the n-th binomial transform of the first row, then the 3rd hyperbinomial transform of any diagonal results in the 3rd diagonal lower in the table.

Examples

			Rows begin:
  {1},
  {3,1},
  {15,6,1},
  {108,45,9,1},
  {1029,432,90,12,1},
  {12288,5145,1080,150,15,1},
  {177147,73728,15435,2160,225,18,1},
  {3000000,1240029,258048,36015,3780,315,21,1},..
		

Crossrefs

Cf. A089464(row sums), A089465(diagonal), A089460, A088956.

Programs

  • Mathematica
    Flatten[Table[3(n-k+3)^(n-k-1) Binomial[n,k],{n,0,10},{k,0,n}]] (* Harvey P. Dale, Jun 26 2013 *)
  • PARI
    for(n=0,10, for(k=0,n, print1(3*(n-k+3)^(n-k-1)*binomial(n,k), ", "))) \\ G. C. Greubel, Nov 17 2017

Formula

T(n, k) = 3*(n-k+3)^(n-k-1)*C(n, k).
E.g.f.: exp(x*y)*(-LambertW(-y)/y)^3.
Note: (-LambertW(-y)/y)^3 = Sum_{n>=0} 3*(n+3)^(n-1)*y^n/n!.

A362523 a(n) = n! * Sum_{k=0..floor(n/3)} (k+1)^(k-1) / (k! * (n-3*k)!).

Original entry on oeis.org

1, 1, 1, 7, 25, 61, 1201, 7771, 30577, 1058905, 9904321, 53722351, 2708688841, 33126146197, 228967340785, 15262865820931, 230517745701601, 1936173471789361, 161021598306402817, 2894434429492525015, 28614958982310290041
Offset: 0

Views

Author

Seiichi Manyama, Apr 23 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^3))))

Formula

E.g.f.: exp(x - LambertW(-x^3)) = -LambertW(-x^3)/x^3 * exp(x).
a(n) ~ sqrt(3) * (exp(3*exp(-1/3)/2) + 2*cos(sqrt(3)*exp(-1/3)/2 - 2*Pi*n/3)) * n^(n-1) / exp(2*n/3 + exp(-1/3)/2 - 1). - Vaclav Kotesovec, Aug 05 2025

A218496 4th iteration of the hyperbinomial transform on the sequence of 1's.

Original entry on oeis.org

1, 5, 33, 281, 2993, 38705, 592489, 10516441, 212841889, 4845154913, 122664558905, 3421333467689, 104297273041969, 3451364116327249, 123251578626936841, 4725537745859375705, 193647372258547916609, 8447809104669814884545, 390938955429073736493145
Offset: 0

Views

Author

Alois P. Heinz, Oct 30 2012

Keywords

Comments

See A088956 for the definition of the hyperbinomial transform.

Crossrefs

Column k=4 of A144303.

Programs

  • Maple
    a:= n-> add(4*(n-j+4)^(n-j-1)*binomial(n,j), j=0..n):
    seq (a(n), n=0..20);

Formula

E.g.f.: exp(x) * (-LambertW(-x)/x)^4.
a(n) = Sum_{j=0..n} 4 * (n-j+4)^(n-j-1) * C(n,j).
Hyperbinomial transform of A089464.
a(n) ~ 4*exp(4+exp(-1))*n^(n-1). - Vaclav Kotesovec, Aug 16 2013
Showing 1-4 of 4 results.