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 1-6 of 6 results.

A243752 Number T(n,k) of Dyck paths of semilength n having exactly k (possibly overlapping) occurrences of the consecutive step pattern given by the binary expansion of n, where 1=U=(1,1) and 0=D=(1,-1); triangle T(n,k), n>=0, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 1, 3, 1, 1, 11, 2, 9, 16, 12, 4, 1, 1, 57, 69, 5, 127, 161, 98, 35, 7, 1, 323, 927, 180, 1515, 1997, 1056, 280, 14, 4191, 5539, 3967, 1991, 781, 244, 64, 17, 1, 1, 10455, 25638, 18357, 4115, 220, 1, 20705, 68850, 77685, 34840, 5685, 246, 1
Offset: 0

Views

Author

Alois P. Heinz, Jun 09 2014

Keywords

Examples

			Triangle T(n,k) begins:
: n\k :    0     1     2     3    4    5  ...
+-----+----------------------------------------------------------
:  0  :    1;                                 [row  0 of A131427]
:  1  :    0,    1;                           [row  1 of A131427]
:  2  :    0,    1,    1;                     [row  2 of A090181]
:  3  :    1,    3,    1;                     [row  3 of A001263]
:  4  :    1,   11,    2;                     [row  4 of A091156]
:  5  :    9,   16,   12,    4,   1;          [row  5 of A091869]
:  6  :    1,   57,   69,    5;               [row  6 of A091156]
:  7  :  127,  161,   98,   35,   7,   1;     [row  7 of A092107]
:  8  :  323,  927,  180;                     [row  8 of A091958]
:  9  : 1515, 1997, 1056,  280,  14;          [row  9 of A135306]
: 10  : 4191, 5539, 3967, 1991, 781, 244, ... [row 10 of A094507]
		

Crossrefs

A131428 a(n) = 2*C(n) - 1, where C(n) = A000108(n) are the Catalan numbers.

Original entry on oeis.org

1, 1, 3, 9, 27, 83, 263, 857, 2859, 9723, 33591, 117571, 416023, 1485799, 5348879, 19389689, 70715339, 259289579, 955277399, 3534526379, 13128240839, 48932534039, 182965127279, 686119227299, 2579808294647, 9723892802903, 36734706144303, 139067101832007
Offset: 0

Views

Author

Gary W. Adamson, Jul 10 2007

Keywords

Comments

Starting (1, 3, 9, 27, 83, ...), = row sums of triangle A136522. - Gary W. Adamson, Jan 02 2008
Hankel transform is A171552. - Paul Barry, Dec 11 2009
Apparently, for n >= 1, the maximum peak height minus the maximum valley height summed over all Dyck n-paths (with max valley height deemed zero if no valleys). - David Scambler, Oct 05 2012
Apparently for n > 1 the number of fixed points in all Dyck (n-1)-paths. A fixed point occurs when a vertex of a Dyck k-path is also a vertex of the path U^kD^k. - David Scambler, May 01 2013

Examples

			a(3) = 9 = 2*C(3) - 1 = 2*5 - 1, where C refers to the Catalan numbers, A000108.
		

Crossrefs

Programs

  • GAP
    List([0..25], n-> 2*Binomial(2*n,n)/(n+1) - 1); # G. C. Greubel, Aug 12 2019
  • Magma
    [2*Catalan(n) -1: n in [0..25]]; // G. C. Greubel, Aug 12 2019
    
  • Maple
    seq(2*binomial(2*n,n)/(n+1)-1, n=0..25); # Emeric Deutsch, Jul 25 2007
  • Mathematica
    2CatalanNumber[Range[0,25]]-1  (* Harvey P. Dale, Apr 17 2011 *)
  • PARI
    vector(25, n, n--; 2*binomial(2*n,n)/(n+1) - 1) \\ G. C. Greubel, Aug 12 2019
    
  • Sage
    [2*catalan_number(n) -1 for n in (0..25)] # G. C. Greubel, Aug 12 2019
    

Formula

Right border of triangle A131429.
From Emeric Deutsch, Jul 25 2007: (Start)
a(n) = 2*binomial(2*n,n)/(n+1) - 1.
G.f.: (1-sqrt(1-4*x))/x - 1/(1-x). (End)
(1, 3, 9, 27, 83, ...) = row sums of A118976. - Gary W. Adamson, Aug 31 2007
Row sums of triangle A131428 starting (1, 3, 9, 27, 83, ...). - Gary W. Adamson, Aug 31 2007
Starting with offset 1 = Narayana transform (A001263) of [1,2,2,2,...]. - Gary W. Adamson, Jul 29 2011
D-finite with recurrence (n+1)*a(n) +2*(-2*n+1)*a(n-1) +3*(-n+1)=0. - R. J. Mathar, Nov 22 2024
a(n) = Sum_{k=0..n} ( binomial(n,k) - binomial(n,k-1) )^2 = Sum_{k=0..n} A080233(n,k)^2 = Sum_{k=0..n} A156644(n,k)^2. - Seiichi Manyama, Mar 25 2025

Extensions

More terms from Emeric Deutsch, Jul 25 2007

A085880 Triangle T(n,k) read by rows: multiply row n of Pascal's triangle (A007318) by the n-th Catalan number (A000108).

Original entry on oeis.org

1, 1, 1, 2, 4, 2, 5, 15, 15, 5, 14, 56, 84, 56, 14, 42, 210, 420, 420, 210, 42, 132, 792, 1980, 2640, 1980, 792, 132, 429, 3003, 9009, 15015, 15015, 9009, 3003, 429, 1430, 11440, 40040, 80080, 100100, 80080, 40040, 11440, 1430, 4862, 43758, 175032, 408408, 612612, 612612, 408408, 175032, 43758, 4862
Offset: 0

Views

Author

N. J. A. Sloane, Aug 17 2003

Keywords

Comments

Coefficients of terms in the series reversion of (1-k*x-(k+1)*x^2)/(1+x). - Paul Barry, May 21 2005
Equals A131427 * A007318 as infinite lower triangular matrices. [Philippe Deléham, Sep 15 2008]
Sum_{k=0..n} T(n,k)*x^k = A168491(n), A000007(n), A000108(n), A151374(n), A005159(n), A151403(n), A156058(n), A156128(n), A156266(n), A156270(n), A156273(n), A156275(n) for x = -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 respectively. - Philippe Deléham, Nov 15 2013
Diagonal sums are A052709(n+1). - Philippe Deléham, Nov 15 2013

Examples

			Triangle starts:
[ 1]     1;
[ 2]     1,     1;
[ 3]     2,     4,      2;
[ 4]     5,    15,     15,      5;
[ 5]    14,    56,     84,     56,     14;
[ 6]    42,   210,    420,    420,    210,     42;
[ 7]   132,   792,   1980,   2640,   1980,    792,    132;
[ 8]   429,  3003,   9009,  15015,  15015,   9009,   3003,    429;
[ 9]  1430, 11440,  40040,  80080, 100100,  80080,  40040,  11440,  1430;
[10]  4862, 43758, 175032, 408408, 612612, 612612, 408408, 175032, 43758, 4862;
...
		

Programs

  • GAP
    Flat(List([0..10], n-> List([0..n], k-> Binomial(n,k)*Binomial(2*n,n)/( n+1) ))); # G. C. Greubel, Feb 07 2020
  • Magma
    [Binomial(n,k)*Catalan(n): k in [0..n], n in [0..10]]; // G. C. Greubel, Feb 07 2020
    
  • Maple
    seq(seq(binomial(n, k)*binomial(2*n, n)/(n+1), k = 0..n), n = 0..10); # G. C. Greubel, Feb 07 2020
  • Mathematica
    Table[Binomial[n, k]*CatalanNumber[n], {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, Feb 07 2020 *)
  • PARI
    tabl(nn) = {for (n=0, nn, c =  binomial(2*n,n)/(n+1); for (k=0, n, print1(c*binomial(n, k), ", ");); print(););} \\ Michel Marcus, Apr 09 2015
    
  • Sage
    [[binomial(n,k)*catalan_number(n) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Feb 07 2020
    

Formula

Triangle given by [1, 1, 1, 1, 1, 1, ...] DELTA [1, 1, 1, 1, 1, 1, ...] where DELTA is Deléham's operator defined in A084938.
Sum_{k>=0} T(n, k) = A151374(n) (row sums). - Philippe Deléham, Aug 11 2005
G.f.: (1-sqrt(1-4*(x+y)))/(2*(x+y)). - Vladimir Kruchinin, Apr 09 2015

A131429 Triangle read by rows: T(n,k) = C(n) + C(k) - 1 where C(n) = A000108(n) are the Catalan numbers, 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 5, 5, 6, 9, 14, 14, 15, 18, 27, 42, 42, 43, 46, 55, 83, 132, 132, 133, 136, 145, 173, 263, 429, 429, 430, 433, 442, 470, 560, 857, 1430, 1430, 1431, 1434, 1443, 1471, 1561, 1858, 2859, 4862, 4862, 4863, 4866, 4875, 4903, 4993, 5290, 6291, 9723
Offset: 0

Views

Author

Gary W. Adamson, Jul 10 2007

Keywords

Comments

Left column = Catalan numbers, A000108. Right border = 2*A000108 - 1. Row sums = A131430: (1, 2, 7, 25, 88, 311, 1114, ...).

Examples

			First few rows of the triangle are:
   1;
   1,  1;
   2,  2,  3;
   5,  5,  6,  9;
  14, 14, 15, 18, 27;
  42, 42, 43, 46, 55, 83;
  ...
		

Crossrefs

Column k=0 is A000108.
Row sums are A131430.

Programs

  • PARI
    T(n,k)=if(k<=n, binomial(2*n,n)/(n+1) + binomial(2*k,k)/(k+1) - 1, 0) \\ Andrew Howroyd, Sep 01 2018

Formula

Equals (A000012 * A131427) + (A131427 * A000012) - A000012 as infinite lower triangular matrices.

Extensions

Name clarified by Andrew Howroyd, Sep 01 2018

A372001 Array read by descending antidiagonals: A family of generalized Catalan numbers generated by a generalization of Deléham's Delta operator.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 5, 3, 1, 1, 14, 15, 5, 1, 1, 42, 105, 61, 9, 1, 1, 132, 945, 1385, 297, 17, 1, 1, 429, 10395, 50521, 24273, 1585, 33, 1, 1, 1430, 135135, 2702765, 3976209, 485729, 8865, 65, 1, 1, 4862, 2027025, 199360981, 1145032281, 372281761, 10401345, 50881, 129, 1, 1
Offset: 1

Views

Author

Peter Luschny, Apr 21 2024

Keywords

Comments

Deléham's Delta operator is defined in A084938. It maps two sequences (a, b) to a triangle T. The given sequences are the coefficients of the linear function p = a + x*b which is the starting point of a recurrence described in A084938 and implemented in A371637. The generalization given here extends the number of input sequences to any number, mapping (a, b, c, ...) to p = a + x*b + x^2*c ... but leaves the recurrence unchanged.
The result, as said, is a triangle that we can evaluate in two ways: Firstly, we only return the main diagonal. In this case, we created a new sequence from n given sequences. This case is implemented by the function A(n, dim) below.
Alternatively, we return the entire triangle. But since the triangle is irregular, we convert it into a regular one by taking only every n-th term of a row. This case is handled by the function T(n, dim). For the first few triangles generated this way, see the link section.

Examples

			Array starts:
  [0] 1, 1,  2,     5,        14,            42,                132, ...
  [1] 1, 1,  3,    15,       105,           945,              10395, ...
  [2] 1, 1,  5,    61,      1385,         50521,            2702765, ...
  [3] 1, 1,  9,   297,     24273,       3976209,         1145032281, ...
  [4] 1, 1, 17,  1585,    485729,     372281761,       601378506737, ...
  [5] 1, 1, 33,  8865,  10401345,   38103228225,    352780110115425, ...
  [6] 1, 1, 65, 50881, 231455105, 4104215813761, 220579355255364545, ...
.
Seen as a triangle T(n, k) = A(k, n - k):
  [0] [  1]
  [1] [  1,     1]
  [2] [  2,     1,     1]
  [3] [  5,     3,     1,     1]
  [4] [ 14,    15,     5,     1,    1]
  [5] [ 42,   105,    61,     9,    1,  1]
  [6] [132,   945,  1385,   297,   17,  1, 1]
  [7] [429, 10395, 50521, 24273, 1585, 33, 1, 1]
		

Crossrefs

By ascending antidiagonals: A290569.
Family: A000108 (n=0), A001147 (n=1), A000364 (n=2), A216966 (n=3), A227887 (n=4), A337807 (n=5), A337808 (n=6), A337809 (n=7).
Cf. A291333 (main diagonal), A371999 (row sums of triangle).

Programs

  • SageMath
    def GeneralizedDelehamDelta(F, dim, seq=True):  # The algorithm.
        ring = PolynomialRing(ZZ, 'x')
        x = ring.gen()
        A = [sum(F[j](k) * x^j for j in range(len(F))) for k in range(dim)]
        C = [ring(0)] + [ring(1) for i in range(dim)]
        for k in range(dim):
            for n in range(k, 0, -1):
                C[n] = C[n-1] + C[n+1] * A[n-1]
            yield list(C[1])[-1] if seq else list(C[1])
    def F(n):  # Define the input functions.
        def p0(): return lambda n: pow(n, n^0)
        def p(k): return lambda n: pow(n + 1, k)
        return [p0()] + [p(k) for k in range(n + 1)]
    def A(n, dim): # Return only the main diagonal of the triangle.
        return [r for r in GeneralizedDelehamDelta(F(n), dim)]
    for n in range(7): print(A(n, 7))
    def T(n, dim): # Return the regularized triangle.
        R = GeneralizedDelehamDelta(F(n), dim, False)
        return [[r[k] for k in range(0, len(r), n + 1)] for r in R]
    for n in range(0, 4):
        for row in T(n, 6): print(row)

Formula

A = DELTA([x -> (x + 1)^k : 0 <= k <= n]), i.e. here the input functions of the generalized Delta operator are the (shifted) power functions. The returned sequence is the main diagonal of the generated triangle.

A131430 Row sums of triangle A131429.

Original entry on oeis.org

1, 2, 7, 25, 88, 311, 1114, 4050, 14917, 55528, 208459, 787920, 2994655, 11433998, 43824437, 168520201, 649840740, 2512011359, 9731179138, 37768570827, 146833956266, 571711568905, 2229035221824, 8701426599353, 34005503702176, 133030452858279, 520905732440782
Offset: 0

Views

Author

Gary W. Adamson, Jul 10 2007

Keywords

Examples

			a(3) = 25 = sum of row 3 terms of triangle A131429: (5 + 5 + 6 + 9).
		

Crossrefs

Programs

  • PARI
    a(n)={binomial(2*n,n) - n - 1 + sum(k=0, n, binomial(2*k,k)/(k+1))} \\ Andrew Howroyd, Aug 28 2018

Formula

a(n) = binomial(2*n, n) - (n+1) + Sum_{k=0..n} binomial(2*k, k)/(k+1). - Andrew Howroyd, Aug 28 2018

Extensions

Terms a(10) and beyond from Andrew Howroyd, Aug 28 2018
Showing 1-6 of 6 results.