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.

A049385 Triangle of numbers related to triangle A049375; generalization of Stirling numbers of second kind A008277, Lah-numbers A008297...

Original entry on oeis.org

1, 6, 1, 66, 18, 1, 1056, 372, 36, 1, 22176, 9240, 1200, 60, 1, 576576, 271656, 42840, 2940, 90, 1, 17873856, 9269568, 1685376, 142800, 6090, 126, 1, 643458816, 360847872, 73313856, 7254576, 386400, 11256, 168, 1, 26381811456, 15799069440
Offset: 1

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Author

Keywords

Comments

a(n,m) := S2(6; n,m) is the sixth triangle of numbers in the sequence S2(k; n,m), k=1..6: A008277 (unsigned Stirling 2nd kind), A008297 (unsigned Lah), A035342, A035469, A049029, respectively. a(n,1)= A008548(n).
a(n,m) enumerates unordered n-vertex m-forests composed of m plane increasing 6-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

Examples

			Triangle begins:
  {1};
  {6,1};
  {66,18,1};
  {1056,372,36,1};
  ...
		

Crossrefs

Cf. A049412.

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    # Adds (1,0,0,0, ..) as column 0.
    BellMatrix(n -> mul(5*k+1, k=0..n), 9); # Peter Luschny, Jan 28 2016
  • Mathematica
    a[n_, m_] := n!*Coefficient[Series[((-1 + (1 - 5*x)^(-1/5))^m)/m!, {x, 0, n}], x^n];
    Flatten[Table[a[n, m], {n, 1, 9}, {m, 1, n}]][[1 ;; 38]]
    (* Jean-François Alcover, Jun 21 2011, after e.g.f. *)
    rows = 9;
    t = Table[Product[5k+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) = n!*A049375(n, m)/(m!*5^(n-m)); a(n+1, m) = (5*n+m)*a(n, m)+ a(n, m-1), n >= m >= 1; a(n, m) := 0, n
a(n, m) = sum(|A051150(n, j)|*S2(j, m), j=m..n) (matrix product), with S2(j, m) := A008277(j, m) (Stirling2 triangle). Priv. comm. to 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.

A039746 Row sums of triangle A049375.

Original entry on oeis.org

1, 16, 306, 6321, 136311, 3021276, 68250216, 1563397131, 36195839771, 845073322136, 19864512260726, 469561887175791, 11151848709622581, 265910204875935096, 6362320059617532336, 152684022853771521426
Offset: 1

Keywords

Formula

G.f. (1-(1-25*x)^(1/5))/(6*(1-25*x)^(1/5)-1) = p(x)/(1-p(x)) where p(x)= (-1+(1-25*x)^(-1/5))/5 ( G.f. for first column of A049375).

A092083 A convolution triangle of numbers obtained from A034789.

Original entry on oeis.org

1, 21, 1, 546, 42, 1, 15561, 1533, 63, 1, 466830, 54054, 2961, 84, 1, 14471730, 1885338, 124740, 4830, 105, 1, 458960580, 65542932, 4977882, 236880, 7140, 126, 1, 14801478705, 2277656901, 192582117, 10661301, 399735, 9891, 147, 1
Offset: 1

Author

Wolfdieter Lang, Mar 19 2004

Keywords

Comments

a(n,1) = A034789(n). a(n,m)=: s2(7; n,m), a member of a sequence of unsigned triangles including s2(2; n,m)=A007318(n-1,m-1) (Pascal's triangle). s2(3; n,m)= A035324(n,m), s2(4; n,m)= A035529(n,m), s2(5; n,m)= A048882(n,m), s2(6; n,m)= A049375.

Examples

			{1}; {21,1}; {546,42,1}; {15561,1533,63,1}; ...
		

Crossrefs

Cf. A092086 (row sums), A092087 (alternating row sums).

Formula

a(n, m) = 6*(6*(n-1)+m)*a(n-1, m)/n + m*a(n-1, m-1)/n, n >= m >= 1; a(n, m) := 0, n

A132057 A convolution triangle of numbers obtained from A034904.

Original entry on oeis.org

1, 28, 1, 980, 56, 1, 37730, 2744, 84, 1, 1531838, 130340, 5292, 112, 1, 64337196, 6136956, 299782, 8624, 140, 1, 2766499428, 288408120, 16120314, 568008, 12740, 168, 1, 121034349975, 13561837212, 841627332, 34401528, 956970, 17640, 196, 1
Offset: 1

Author

Wolfdieter Lang Sep 14 2007

Keywords

Comments

a(n,1) = A034904(n). a(n,m)=: s2(8; n,m), a member of a sequence of unsigned triangles including s2(2; n,m)=A007318(n-1,m-1) (Pascal's triangle). s2(3;n,m)= A035324(n,m), s2(4; n,m)= A035529(n,m), s2(5; n,m)= A048882(n,m), s2(6; n,m)= A049375; s2(7; n,m)=A092083.

Examples

			{1}; {28,1}; {980,56,1}; (37730,2744,84,1);...
		

Crossrefs

Cf. A132058 (row sums), A132059 (negative of alternating row sums).

Programs

  • Mathematica
    a[n_, m_] := a[n, m] = 7*(7*(n-1) + m)*a[n-1, m]/n + m*a[n-1, m-1]/n;
    a[n_, m_] /; n < m = 0; a[_, 0] = 0; a[1, 1] = 1;
    Flatten[Table[a[n, m], {n, 1, 8}, {m, 1, n}]][[1 ;; 36]]
    (* Jean-François Alcover, Jun 17 2011 *)

Formula

a(n, m) = 7*(7*(n-1)+m)*a(n-1, m)/n + m*a(n-1, m-1)/n, n >= m >= 1; a(n, m) := 0, n
G.f. for m-th column: ((-1+(1-49*x)^(-1/7))/7)^m.
Showing 1-4 of 4 results.