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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A362849 Triangle read by rows, T(n, k) = A243664(n) * binomial(n, k).

Original entry on oeis.org

1, 1, 1, 21, 42, 21, 1849, 5547, 5547, 1849, 426405, 1705620, 2558430, 1705620, 426405, 203374081, 1016870405, 2033740810, 2033740810, 1016870405, 203374081, 173959321557, 1043755929342, 2609389823355, 3479186431140, 2609389823355, 1043755929342, 173959321557
Offset: 0

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Author

Peter Luschny, May 05 2023

Keywords

Examples

			[0]         1;
[1]         1,          1;
[2]        21,         42,         21;
[3]      1849,       5547,       5547,       1849;
[4]    426405,    1705620,    2558430,    1705620,     426405;
[5] 203374081, 1016870405, 2033740810, 2033740810, 1016870405, 203374081;
		

Crossrefs

Family of triangles: A055372 (m=0, Pascal), A362585 (m=1, Fubini), A362586 (m=2, Joffe), this sequence (m=3, A278073).
Cf. A243664 (column 0 and main diagonal).

Programs

  • SageMath
    # uses[TransOrdPart from A362585]
    def A362849(n) -> list[int]: return TransOrdPart(3, n)
    for n in range(6): print(A362849(n))

A055373 Invert transform applied twice to Pascal's triangle A007318.

Original entry on oeis.org

1, 1, 1, 3, 6, 3, 9, 27, 27, 9, 27, 108, 162, 108, 27, 81, 405, 810, 810, 405, 81, 243, 1458, 3645, 4860, 3645, 1458, 243, 729, 5103, 15309, 25515, 25515, 15309, 5103, 729, 2187, 17496, 61236, 122472, 153090, 122472, 61236, 17496, 2187, 6561
Offset: 0

Views

Author

Christian G. Bower, May 16 2000

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows, given by [1, 2, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 2, 0, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Aug 10 2005
T(n,k) is the number of sequences of nonempty sequences of nonempty bit strings with n bits and exactly k 1's over all strings in the sequence of sequences. In other words, these are sequences of the structures counted by A055372. - Geoffrey Critzer, Apr 06 2013

Examples

			Triangle begins:
   1;
   1,   1;
   3,   6,   3;
   9,  27,  27,   9;
  27, 108, 162, 108,  27;
  ...
		

Crossrefs

Programs

  • Mathematica
    nn=10;f[list_]:=Select[list,#>0&];a=(x+y x)/(1-(x+y x));b=1/(1-a);Map[f,CoefficientList[Series[1/(2-b),{x,0,nn}],{x,y}]]//Grid  (* Geoffrey Critzer, Apr 06 2013 *)

Formula

T(n,k) = 3^(n-1)*C(n, k) for n > 0.
O.g.f.: 1/(2 - A(x,y)) where A(x,y) is the o.g.f. for A055372. - Geoffrey Critzer, Apr 06 2013

A055374 Invert transform applied three times to Pascal's triangle A007318.

Original entry on oeis.org

1, 1, 1, 4, 8, 4, 16, 48, 48, 16, 64, 256, 384, 256, 64, 256, 1280, 2560, 2560, 1280, 256, 1024, 6144, 15360, 20480, 15360, 6144, 1024, 4096, 28672, 86016, 143360, 143360, 86016, 28672, 4096, 16384, 131072, 458752, 917504, 1146880, 917504
Offset: 0

Views

Author

Christian G. Bower, May 16 2000

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows, given by [1, 3, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 3, 0, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Aug 10 2005

Examples

			   1;
   1,   1;
   4,   8,   4;
  16,  48,  48,  16;
  64, 256, 384, 256, 64; ...
		

Crossrefs

Formula

a(n,k) = 4^(n-1)*C(n, k), for n>0.
G.f.: (-1+3*x+3*x*y)/(-1+4*x+4*x*y). - R. J. Mathar, Aug 12 2015

A143376 Triangle read by rows: T(n,k) is the number of unordered pairs of vertices at distance k in the cube Q_n of dimension n (1 <= k <= n).

Original entry on oeis.org

1, 4, 2, 12, 12, 4, 32, 48, 32, 8, 80, 160, 160, 80, 16, 192, 480, 640, 480, 192, 32, 448, 1344, 2240, 2240, 1344, 448, 64, 1024, 3584, 7168, 8960, 7168, 3584, 1024, 128, 2304, 9216, 21504, 32256, 32256, 21504, 9216, 2304, 256, 5120, 23040, 61440, 107520
Offset: 1

Views

Author

Emeric Deutsch, Sep 05 2008

Keywords

Comments

Sum of entries in row n = 2^(n-1)*(2^n-1) = A006516.
The entries in row n are the coefficients of the Wiener polynomial of the cube Q_n.
Sum_{k=1..n} k*T(n,k) = n*4^(n-1) = A002697(n) = the Wiener index of the cube Q_n.
Triangle T(n,k), 1 <= k <= n, read by rows given by [1,1,0,0,0,0,0,...]DELTA[1,1,0,0,0,0,0,...] where DELTA is the operator defined in A084938; subtriangle of triangle A055372. - Philippe Deléham, Oct 14 2008

Examples

			T(2,1)=4, T(2,2)=2 because in Q_2 (a square) there are 4 distances equal to 1 and 2 distances equal to 2.
Triangle starts:
   1;
   4,   2;
  12,  12,   4;
  32,  48,  32,   8;
  80, 160, 160,  80,  16;
		

Crossrefs

Programs

  • Maple
    T:=proc(n,k) options operator, arrow: 2^(n-1)*binomial(n,k) end proc: for n to 10 do seq(T(n,k),k=1..n) end do; # yields sequence in triangular form
  • Mathematica
    nn = 8; A[u_, z_] := (z + u z)/(1 - (z + u z));
    Drop[Map[Select[#, # > 0 &] &, Map[Drop[#, 1] &,CoefficientList[Series[1/(1 - A[u, z]), {z, 0, nn}], {z, u}]]],1] // Grid (* Geoffrey Critzer, Mar 04 2017 *)
    Flatten[Table[2^(n-1) Binomial[n, k], {n, 10},{k,n}]] (* Indranil Ghosh, Mar 06 2017 *)
  • PARI
    tabl(nn) = {for (n=1, nn, for(k=1, n, print1(2^(n-1) * binomial(n, k),", ");); print();); };
    tabl(10); \\ Indranil Ghosh, Mar 06 2017
    
  • Python
    import math
    f=math.factorial
    def C(n,r): return f(n) / f(r) / f(n-r)
    i=1
    for n in range(1,126):
        for k in range(1,n+1):
            print(str(i)+" "+str(2**(n-1)*C(n,k)))
            i+=1 # Indranil Ghosh, Mar 06 2017

Formula

T(n,k) = 2^(n-1)*binomial(n,k).
G.f.: G(q,z) = qz/((1-2z)(1-2z-2zq)).
T(n,k) = A055372(n,k). - Philippe Deléham, Oct 14 2008

Extensions

Typo corrected by Philippe Deléham, Jan 05 2009
Previous Showing 11-14 of 14 results.