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 1-9 of 9 results.

A050166 Triangle T(n,k) = M(2n,k,-1), with 0 <= k <= n, n >= 0, and array M is defined in A050144.

Original entry on oeis.org

1, 1, 2, 1, 4, 5, 1, 6, 14, 14, 1, 8, 27, 48, 42, 1, 10, 44, 110, 165, 132, 1, 12, 65, 208, 429, 572, 429, 1, 14, 90, 350, 910, 1638, 2002, 1430, 1, 16, 119, 544, 1700, 3808, 6188, 7072, 4862, 1, 18, 152, 798, 2907, 7752, 15504, 23256, 25194, 16796
Offset: 0

Views

Author

Keywords

Comments

Sometimes called Catalan's triangle, although this term is usually reserved for several other triangles!
T is a mirror image of the array in A039598.
Given (1) = row 0, then the sum of terms with alternating signs in row r of A050166 = (-1)^r * A000108(n); where A000108 = 1, 1, 2, 5, 14, 42, ...the Catalan numbers. - Herb Conn
The diagonals of this triangle are self-convolutions of the main diagonal A000108(n+1): 1, 2, 5, 14, 42, 132, 429, ... - Philippe Deléham, May 25 2005
The multiplicities of the eigenvalues of the middle cubes are related to this triangle. The middle cube in Q_3 has eigenvalues -2, -1, 1, 2 with multiplicities 1, 2, 2, 1. The middle cube in Q_5 has eigenvalues -3, -2, -1, 1, 2, 3 with multiplicities 1, 4, 5, 5, 4, 1. The middle cube in Q_7 has eigenvalues -4, -3, -2, -1, 1, 2, 3, 4 with multiplicities 1, 6, 14, 14, 14, 14, 6, 1, etc. - Ke Qiu, Apr 05 2019

Examples

			Triangle begins:
  1;
  1,  2;
  1,  4,  5;
  1,  6, 14, 14;
  1,  8, 27, 48, 42;
  ...
		

References

  • Boris A. Bondarenko, Generalized Pascal Triangles and Pyramids (in Russian), FAN, Tashkent, 1990, ISBN 5-648-00738-8.
  • Y. Jiang, K. Qiu, R. Qiu, and J. Shen, On the spectrum of the middle-cube, Congressus Numerantium, 195 (2009), 195-204.
  • A. Nkwanta, Lattice paths and RNA secondary structures, in: Nathaniel Dean, African Americans in Mathematics, AMS and DIMACS, 1997, ISBN 978-0-8218-0678-4, pp. 137-147.

Crossrefs

Mirror image of A039598.

Programs

  • GAP
    Flat(List([0..10], n-> List([0..n], k-> 2*(n-k+1)* Binomial(2*n+1, k)/(2*n-k+2) ))); # G. C. Greubel, Apr 05 2019
  • Magma
    [[2*(n-k+1)*Binomial(2*n+1,k)/(2*n-k+2): k in [0..n]]: n in [0..10]]; // G. C. Greubel, Apr 05 2019
    
  • Mathematica
    Table[2*Binomial[2n+1, k]*(n-k+1)/(2*n-k+2), {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, Apr 05 2019 *)
  • PARI
    {T(n,k) = 2*(n-k+1)*binomial(2*n+1,k)/(2*n-k+2)}; \\ G. C. Greubel, Apr 05 2019
    
  • Sage
    [[2*(n-k+1)*binomial(2*n+1,k)/(2*n-k+2) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Apr 05 2019
    

Formula

From Henry Bottomley, Sep 24 2001: (Start)
T(n, k) = C(2n+1, k)*2*(n-k+1)/(2n-k+2) = A039598(n, n-k)
T(n, k) = T(n-1, k) + 2*T(n-1, k-1) + T(n-1, k-2), with T(0, 0) = 1 and T(n, k) = 0 if n < 0 or n < k. (End)
Sum_{0<=k<=n} T(n,k)*x^k = A000012(n), A001700(n), A194723(n+1), A194724(n+1), A194725(n+1), A194726(n+1), A195727(n+1), A194728(n+1), A194729(n+1), A194730(n+1) for x = 0,1,2,3,4,5,6,7,8,9 respectively. - Philippe Deléham, Nov 03 2011

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Mar 14 2001

A050165 Triangle read by rows: T(n,k) = M(2n+1,k,-1), 0 <= k <= n, n >= 0, array M as in A050144.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 5, 9, 5, 1, 7, 20, 28, 14, 1, 9, 35, 75, 90, 42, 1, 11, 54, 154, 275, 297, 132, 1, 13, 77, 273, 637, 1001, 1001, 429, 1, 15, 104, 440, 1260, 2548, 3640, 3432, 1430, 1, 17, 135, 663, 2244, 5508, 9996, 13260, 11934
Offset: 0

Views

Author

Keywords

Comments

T is a mirror image of the array in A039599.

Examples

			Triangle begins:
  1;
  1,  1;
  1,  3,  2;
  1,  5,  9,   5;
  1,  7, 20,  28,  14;
  1,  9, 35,  75,  90,  42;
  1, 11, 54, 154, 275, 297, 132;
		

Crossrefs

Formula

Triangle T(n, k) read by rows; given by [1, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 1, 1, 1, 1, 1, 1, 1, 1, ...] where DELTA is the operator defined in A084938. T(n, k) = C(2n, k)*(2n-2k+1)/(2n-k+1). - Philippe Deléham, Dec 07 2003
Sum_{k=0..min(m, n)} T(m, m-k)*T(n, n-k) = A000108(m+n); A000108: Catalan numbers. - Philippe Deléham, Dec 30 2003
T(n, k) = 0 if n < k, T(n, n)= A000108(n) and for n > k: T(n, k) = Sum_{j=0..k} T(n-1-j, k-j)*A000108(j+1). - Philippe Deléham, Feb 03 2004
T(n,k)= Sum_{j>=0} (-1)^(n-j)*A094385(n,j)*binomial(j,k). - Philippe Deléham, May 05 2007
T(2n,n) = A126596(n). - Philippe Deléham, Nov 23 2011

A050153 T(n,k)=M(2n+1,n-1,k-1), 0<=k<=n, n >= 0, array M as in A050144.

Original entry on oeis.org

0, 1, 0, 3, 1, 1, 9, 5, 6, 1, 28, 20, 27, 8, 1, 90, 75, 110, 44, 10, 1, 297, 275, 429, 208, 65, 12, 1, 1001, 1001, 1638, 910, 350, 90, 14, 1, 3432, 3640, 6188, 3808, 1700, 544, 119, 16, 1
Offset: 0

Views

Author

Keywords

Examples

			Rows: {0}; {1,0}; {3,1,1}; ...
		

A050145 T(n,k)=M(2n,n-1,k-1), 0<=k<=n, n >= 0, array M as in A050144.

Original entry on oeis.org

0, 1, 0, 2, 1, 1, 5, 4, 5, 1, 14, 14, 20, 7, 1, 42, 48, 75, 35, 9, 1, 132, 165, 275, 154, 54, 11, 1, 429, 572, 1001, 637, 273, 77, 13, 1, 1430, 2002, 3640, 2548, 1260, 440, 104, 15, 1, 4862, 7072, 13260, 9996, 5508, 2244, 663, 135, 17, 1
Offset: 0

Views

Author

Keywords

Comments

First 7 columns of T are A000108, A002057, A000344, A000588, A001392, A000589, A000590.

Examples

			Rows: {0}; {1,0}; {2,1,1}; ...
		

A050154 T(n,k)=M(2n+2,n-1,k-1), 0<=k<=n, n >= 0, array M as in A050144.

Original entry on oeis.org

0, 1, 0, 4, 1, 1, 14, 6, 7, 1, 48, 27, 35, 9, 1, 165, 110, 154, 54, 11, 1, 572, 429, 637, 273, 77, 13, 1, 2002, 1638, 2548, 1260, 440, 104, 15, 1, 7072, 6188, 9996, 5508, 2244, 663, 135, 17, 1
Offset: 0

Views

Author

Keywords

Examples

			Rows: {0}; {1,0}; {4,1,1}; ...
		

A050156 T(n,k)=M(2n+3,n+3,k+3), 0<=k<=n, n >= 0, array M as in A050144.

Original entry on oeis.org

1, 4, 1, 14, 6, 1, 48, 27, 8, 1, 165, 110, 44, 10, 1, 572, 429, 208, 65, 12, 1, 2002, 1638, 910, 350, 90, 14, 1, 7072, 6188, 3808, 1700, 544, 119, 16, 1, 25194, 23256, 15504, 7752, 2907, 798, 152, 18, 1
Offset: 0

Views

Author

Keywords

Examples

			Rows: {1}; {4,1}; {14,6,1}; ...
		

A050167 T(n,k)=M(n,k,f(n,k)), 0<=k<=n, n >= 0, array M as in A050144 and f(n,k)=least number t for which M(n,k,t) is not 0.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 3, 1, 1, 3, 2, 5, 4, 1, 1, 4, 5, 5, 9, 5, 1, 1, 5, 9, 5, 14, 14, 6, 1, 1, 6, 14, 14, 14, 28, 20, 7, 1, 1, 7, 20, 28, 14, 42, 48, 27, 8, 1, 1, 8, 27, 48, 42, 42, 90, 75, 35, 9, 1, 1, 9, 35, 75, 90, 42, 132, 165, 110, 44
Offset: 0

Views

Author

Keywords

Comments

f(n,k)=-1 if 0<=k<=[ (n-1)/2 ], f(n,k)=2k-n if [ (n+1)/2 ]+1<=k<=n.

Examples

			Rows: {1}; {1,1}; {1,1,1}; {1,1,2,1}, ...
		

A050155 Triangle T(n,k), k>=0 and n>=1, read by rows defined by: T(n,k) = (2k+3)*binomial(2n,n-k-1)/(n+k+2).

Original entry on oeis.org

1, 3, 1, 9, 5, 1, 28, 20, 7, 1, 90, 75, 35, 9, 1, 297, 275, 154, 54, 11, 1, 1001, 1001, 637, 273, 77, 13, 1, 3432, 3640, 2548, 1260, 440, 104, 15, 1, 11934, 13260, 9996, 5508, 2244, 663, 135, 17, 1, 41990, 48450, 38760, 23256, 10659, 3705, 950, 170, 19, 1
Offset: 1

Views

Author

Keywords

Comments

T(n-2k-1,k) = number of n-th generation vertices in the tree of sequences with unit increase labeled by 2k+2 (cf. Zoran Sunic reference) . - Benoit Cloitre, Oct 07 2003
Number of lattice paths from (0,0) to (n,n) with steps E=(1,0) and N=(0,1) which touch but do not cross the line x-y=k+1 . - Herbert Kociemba, May 24 2004
Number of standard tableaux of shape (n+k+1, n-k-1). - Emeric Deutsch, May 30 2004
Riordan array (c(x)^3,xc(x)^2) where c(x) is the g.f. of A000108. Inverse array is A109954. - Paul Barry, Jul 06 2005

Examples

			    1;
    3,   1;
    9,   5,   1;
   28,  20,   7,  1;
   90,  75,  35,  9,  1;
  297, 275, 154, 54, 11, 1;
  ...
		

Crossrefs

Cf. A000108, A001791 (row sums), A050144.

Programs

  • Maple
    T:= (n, k)->  (2*k+3)*binomial(2*n, n-k-1)/(n+k+2):
    seq(seq(T(n, k), k=0..n-1), n=1..10);  # Alois P. Heinz, Jan 19 2013
  • Mathematica
    T[n_, k_] :=  (2*k + 3)*Binomial[2*n, n - k - 1]/(n + k + 2);
    Table[T[n, k], {n, 1, 10}, {k, 0, n - 1}] // Flatten (* Jean-François Alcover, May 21 2016 *)

Formula

Sum_{ k = 0, .., n-1} T(n, k) = binomial(2n, n-1) = A001791(n).
G.f. of column k: x^(k+1)*C^(2*k+3) where C = (1-(1-4*x)^(1/2))/(2*x) is the g.f. of Catalan numbers A000108. - Philippe Deléham, Feb 03 2004
T(n, k) = A039599(n, k+1) = A009766(n+k+1, n-k-1) = A033184(n+k+2, 2k+3) . - Philippe Deléham, May 28 2005
Sum_{k>= 0} T(m, k)*T(n, k) = A000108(m+n) - A000108(m)*A000108(n). - Philippe Deléham, May 28 2005
T(n, k)=(2k+3)binomial(2n+2, n+k+2)/(n+k+3)=C(2n+2, n+k+2)-C(2n+2, n+k+3) [offset (0, 0)]. - Paul Barry, Jul 06 2005

Extensions

Edited by Philippe Deléham, May 22 2005

A050159 T(n,k) = S(2n-1,n-1,k-1), 0<=k<=n, n >= 0, array S as in A050157.

Original entry on oeis.org

0, 1, 1, 1, 2, 3, 2, 5, 9, 10, 5, 14, 28, 34, 35, 14, 42, 90, 117, 125, 126, 42, 132, 297, 407, 451, 461, 462, 132, 429, 1001, 1430, 1638, 1703, 1715, 1716, 429, 1430, 3432, 5070, 5980, 6330, 6420, 6434, 6435, 1430, 4862, 11934, 18122
Offset: 0

Views

Author

Keywords

Examples

			Rows: {0}; {1,1}; {1,2,3}; ...
		

Crossrefs

Formula

T(n, k) = Sum_{t(n, j): 0<=j<=k}, array t as in A050144.
Showing 1-9 of 9 results.