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.

A092082 Triangle of numbers related to triangle A092083; generalization of Stirling numbers of second kind A008277, Lah-numbers A008297, ...

Original entry on oeis.org

1, 7, 1, 91, 21, 1, 1729, 511, 42, 1, 43225, 15015, 1645, 70, 1, 1339975, 523705, 69300, 4025, 105, 1, 49579075, 21240765, 3226405, 230300, 8330, 147, 1, 2131900225, 984172735, 166428990, 13820205, 621810, 15386, 196, 1, 104463111025
Offset: 1

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Author

Wolfdieter Lang, Mar 19 2004

Keywords

Comments

a(n,m) := S2(7; n,m) is the seventh triangle of numbers in the sequence S2(k;n,m), k=1..6: A008277 (unsigned Stirling 2nd kind), A008297 (unsigned Lah), A035342, A035469, A049029, A049385, respectively. a(n,1)=A008542(n), n>=1.
a(n,m) enumerates unordered n-vertex m-forests composed of m plane increasing 7-ary trees. Proof based on the a(n,m) recurrence. See also the F. Bergeron et al. reference, especially Table 1, first row and Example 1 for the e.g.f. for m=1. - Wolfdieter Lang, Sep 14 2007
Also the Bell transform of A008542(n+1). For the definition of the Bell transform see A264428. - Peter Luschny, Jan 26 2016

Examples

			{1}; {7,1}; {91,21,1}; {1729,511,42,1}; ...
		

Crossrefs

Cf. A092084 (row sums), A092085 (alternating row sums).

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    # Adds (1, 0, 0, 0, ..) as column 0.
    BellMatrix(n -> mul(6*k+1, k=0..n), 9); # Peter Luschny, Jan 26 2016
  • Mathematica
    mmax = 9; a[n_, m_] := n!*Coefficient[Series[((-1 + (1 - 6*x)^(-1/6))^m)/m!, {x, 0, mmax}], x^n];
    Flatten[Table[a[n, m], {n, 1, mmax}, {m, 1, n}]][[1 ;; 37]] (* Jean-François Alcover, Jun 22 2011, after e.g.f. *)
    rows = 9;
    t = Table[Product[6k+1, {k, 0, n}], {n, 0, rows}];
    T[n_, k_] := BellY[n, k, t];
    Table[T[n, k], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 22 2018, after Peter Luschny *)

Formula

a(n, m) = sum(|A051151(n, j)|*S2(j, m), j=m..n) (matrix product), with S2(j, m) := A008277(j, m) (Stirling2 triangle). Priv. comm. with Wolfdieter Lang by E. Neuwirth, Feb 15 2001; see also the 2001 Neuwirth reference. See the general comment on products of Jabotinsky matrices given under A035342.
a(n, m) = n!*A092083(n, m)/(m!*6^(n-m)); a(n+1, m) = (6*n+m)*a(n, m)+ a(n, m-1), n >= m >= 1; a(n, m) := 0, n
E.g.f. for m-th column: ((-1+(1-6*x)^(-1/6))^m)/m!.

A092084 Row sums of triangle A092082 (S2(7) Stirling2 generalization).

Original entry on oeis.org

1, 8, 113, 2283, 59956, 1937111, 74285023, 3296959548, 166209034083, 9380840313601, 585971815302336, 40131720225336433, 2990153392901281153, 240791249514701885728, 20839616039099721143561
Offset: 0

Author

Wolfdieter Lang, Mar 19 2004

Keywords

Comments

Generalized Bell numbers B(7,1;n).
Apparently the same as A072402 (apart from offset). - R. J. Mathar, Aug 27 2025

Crossrefs

Cf. A092085 (alternating row sums), A049412 (generalized Bell numbers B(6, 1, n)).

Formula

a(n) = Sum_{m=1..n} A092082(n, m), for n>=1.
E.g.f.: exp(-1+(1-6*x)^(-1/6)) - 1.

A132061 Alternating row sums of triangle A132056 (S2(8), Stirling2 generalization).

Original entry on oeis.org

1, 7, 97, 2015, 55841, 1935719, 80574433, 3915183103, 217530794305, 13603055116679, 945542295992801, 72321915976403807, 6036466379411066977, 545983089637963491175, 53194885608199879974241
Offset: 0

Author

Wolfdieter Lang Sep 14 2007

Keywords

Crossrefs

Cf. A092085 (alternating row sums of S2(7)=A092082).

Formula

a(n)= -sum(A132056(n, m)*(-1)^m, m=1..n), n>=1.
E.g.f.:-(exp(1 - (1-7*x)^(-1/7)) - 1).
Showing 1-3 of 3 results.