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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A323255 The permanent of an n X n Toeplitz matrix M(n) whose first row consists of successive positive integer numbers 2*n - 1, n - 1, ..., 1 and whose first column consists of 2*n - 1, 2*n - 2, ..., n.

Original entry on oeis.org

1, 1, 11, 248, 9968, 638772, 60061657, 7798036000, 1336715859150, 292406145227392, 79483340339739367, 26280500564448081664, 10386012861097225139356, 4834639222955142417477888, 2618110215141486526589786501, 1631888040186649673361825042432, 1159983453675106278249250918734938
Offset: 0

Views

Author

Stefano Spezia, Jan 09 2019

Keywords

Comments

The trace of the matrix M(n) is A000384(n).
The sum of the first row of the matrix M(n) is A034856(n).
The sum of the first column of the matrix M(n) is A000326(n).
For n > 1, the sum of the superdiagonal of the matrix M(n) is A000290(n-1).
For n > 1, the sum of the subdiagonal of the matrix M(n) is A001105(n-1).

Examples

			For n = 1 the matrix M(1) is
   1
with permanent a(1) = 1.
For n = 2 the matrix M(2) is
   3, 1
   2, 3
with permanent a(2) = 11.
For n = 3 the matrix M(3) is
   5, 2, 1
   4, 5, 2
   3, 4, 5
with permanent a(3) = 248.
		

Crossrefs

Cf. A323254 (determinant of matrix M(n)).

Programs

  • Mathematica
    b[i_]:=i; a[n_]:=If[n==0, 1, Permanent[ToeplitzMatrix[Join[{b[2*n-1]}, Array[b, n-1, {2*n-2,n }]], Join[{b[2*n-1]},Array[b, n-1, {n-1,1}]]]]]; Array[a, 16, 0]
  • PARI
    tm(n) = {my(m = matrix(n, n, i, j, if (j==1, 2*n-i, n-j+1))); for (i=2, n, for (j=2, n, m[i, j] = m[i-1, j-1]; ); ); m;}
    a(n) = matpermanent(tm(n)); \\ Stefano Spezia, Dec 11 2019

Extensions

a(0) = 1 prepended by Stefano Spezia, Dec 08 2019

A349736 Binomial coefficients C(m,k) such that C(m,k), C(m,k+1), C(m,k+2) with 0 <= k <= m-2 form an increasing arithmetic progression.

Original entry on oeis.org

7, 1001, 490314, 927983760, 6973199770790, 209769429934732479, 25331521183260952835630, 12289694242827235919344118592, 23955991473971122736214778043009679, 187581456720371323313917970237305876898550, 5898404991626652623457605084827693331568853294440, 744569299056744628602691379013860201165514803170616390880
Offset: 1

Views

Author

Bernard Schott, Nov 28 2021

Keywords

Comments

Exercise A1 of 33rd Putnam Exam in 1972 asked one to prove that there are no four consecutive binomial coefficients C(m,k), C(m,k+1), C(m,k+2), C(m,k+3) in arithmetic progression (see link and reference).
However, as there exist such progressions with 3 terms, this sequence lists the smallest term of these arithmetic progressions.
Three consecutive binomial coefficients form an arithmetic progression iff m = n^2+4n+2, n >= 1 (2nd comment of A008865), and then, corresponding k = (n^2+3n-2)/2. Successive pairs (m,k) are (7,1), (14,4), (23,8), (34,13), (47,19), ...
By symmetry of Pascal's triangle with C(m,k) = C(m,m-k), there exists another decreasing arithmetic progression with the same 3 terms in the same row.
Corresponding common differences are in A349737.

Examples

			For n = 1, row 7 of Pascal's triangle is 1, 7, 21, 35, 35, 21, 7, 1; C(7,1) = 7, C(7,2) = 21 and C(7,3) = 35 form an arithmetic progression with common difference = 14, hence a(3) = 7 = C(7,1).
For n = 2, row 14 is 1, 14, 91, 364, 1001, 2002, 3003, 3432, 3003, 2002, 1001, 364, 91, 14, 1; C(14,4) = 1001 , C(14,5) = 2002 and C(14,6) = 3003 form an arithmetic progression with common difference = 1001, hence a(4) = 1001 = C(14,4).
		

References

  • G. L. Alexanderson, L. F. Klosinski and L. C. Larson, The William Lowell Putnam Mathematical Competition, Problems and Solutions 1965-1984, The Mathematical Association of America, 1985, page 17.

Crossrefs

Programs

  • Maple
    Sequence = seq(binomial(n^2+4*n+2,(n^2+3*n-2)/2), n=1..16);
  • Mathematica
    nterms=15; Table[Binomial[n^2+4n+2, (n^2+3n-2)/2], {n, nterms}] (* Paolo Xausa, Nov 29 2021 *)
  • PARI
    a(n) = binomial(n^2+4*n+2,(n^2+3*n-2)/2) \\ Andrew Howroyd, Oct 29 2023

Formula

a(n) = C(n^2+4n+2,(n^2+3n-2)/2) = C(A008865(n+2),A034856(n)), for n >= 1.
a(n) ~ c*2^(n^2+4*n)/n, where c = 4*sqrt(2/(Pi*e)). - Stefano Spezia, Nov 29 2021

Extensions

Missing a(9) = 23955...79 inserted by Georg Fischer, Oct 29 2023

A101919 Triangle read by rows: T(n,k) is the number of Schroeder paths of length 2n and having k up steps starting at even heights.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 12, 8, 1, 1, 33, 42, 13, 1, 1, 88, 183, 102, 19, 1, 1, 232, 717, 624, 205, 26, 1, 1, 609, 2622, 3275, 1650, 366, 34, 1, 1, 1596, 9134, 15473, 11020, 3716, 602, 43, 1, 1, 4180, 30691, 67684, 64553, 30520, 7483, 932, 53, 1, 1, 10945, 100284, 279106
Offset: 0

Views

Author

Emeric Deutsch, Dec 20 2004

Keywords

Comments

A Schroeder path of length 2n is a lattice path starting from (0,0), ending at (2n,0), consisting only of steps U=(1,1) (up steps), D=(1,-1) (down steps) and H=(2,0) (level steps) and never going below the x-axis (Schroeder paths are counted by the large Schroeder numbers, A006318). Also number of Schroeder paths of length 2n and having k humps. A hump is an up step U followed by 0 or more level steps H followed by a down step D. The T(3,2)=8 Schroeder paths of length 6 and having 2 humps are: H(UD)(UD), (UD)H(UD), (UD)(UD)H, (UD)(UHD), (UD)(UUDD), (UHD)(UD), (UUDD)(UD) and U(UD)(UD)D, the humps being shown between parentheses. Row sums are the large Schroeder numbers (A006318). Column 1 yields the odd-indexed Fibonacci numbers minus 1 (A027941). T(n,n-1)=A034856(n)=binomial(n + 1, 2) + n - 1.
Product A085478*A090181 (Morgan-Voyce times Narayana). [From Paul Barry, Jan 29 2009]

Examples

			T(3,2)=8 because we have HU'DU'D, U'DHU'D, U'DU'DH, U'DU'HD, U'DU'UDD, U'HDU'D, U'UDDU'D and U'UU'DDD, the up steps starting at an even height being shown with a prime sign.
Triangle begins:
1;
1,1;
1,4,1;
1,12,8,1;
1,33,42,13,1;
		

Crossrefs

Programs

  • Maple
    G:=1/2/(-z+z^2)*(-1+z+t*z-z^2+sqrt(1-6*z-2*t*z+11*z^2+2*t*z^2-6*z^3+t^2*z^2-2*t*z^3+z^4)): Gser:=simplify(series(G,z=0,13)): P[0]:=1: for n from 1 to 11 do P[n]:=coeff(Gser,z^n) od: for n from 0 to 11 do seq(coeff(t*P[n],t^k),k=1..n+1) od; # yields the sequence in triangular form

Formula

G.f.=G=G(t, z) satisfies z(1-z)G^2-(1-z-tz+z^2)G+1-z=0.
G.f.: 1/(1-x-xy/(1-x-x/(1-x-xy/(1-x-xy/(1-x-x/(1-x-xy/(1-.... (continued fraction). [From Paul Barry, Jan 29 2009]

A128219 A000012 * A127701. a(1) = 1, a(2) = 2, a(3) = 2; by rows, n-1 terms of 2, 3, 4, ... followed by "n".

Original entry on oeis.org

1, 2, 2, 2, 3, 3, 2, 3, 4, 4, 2, 3, 4, 5, 5, 2, 3, 4, 5, 6, 6, 2, 3, 4, 5, 6, 7, 7, 2, 3, 4, 5, 6, 7, 8, 8, 2, 3, 4, 5, 6, 7, 8, 9, 9, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 12, 2, 3, 4, 5, 6
Offset: 1

Views

Author

Gary W. Adamson, Feb 19 2007

Keywords

Examples

			First few rows of the triangle:
  1;
  2, 2;
  2, 3, 3;
  2, 3, 4, 4;
  2, 3, 4, 5, 5;
  2, 3, 4, 5, 6, 6;
  2, 3, 4, 5, 6, 7, 7;
  ...
		

Crossrefs

Cf. A000012, A127701, A034856 (row sums), A128220.

Programs

  • Mathematica
    trm[i_]:=Join[Range[2,i],{i}]; Flatten[Table[trm[n],{n,13}]] (* Harvey P. Dale, Nov 14 2012 *)

Formula

A000012 * A127701 as infinite lower triangular matrices.

A131819 A131818 * A000012 as infinite lower triangular matrices. Triangle read by rows, partial sums starting from the right of A131818.

Original entry on oeis.org

1, 4, 2, 8, 5, 3, 13, 9, 7, 4, 19, 14, 12, 9, 5, 26, 20, 18, 15, 11, 6, 34, 27, 25, 22, 18, 13, 7, 43, 35, 33, 30, 26, 21, 15, 8, 53, 44, 42, 39, 35, 30, 24, 17, 9, 64, 54, 52, 49, 45, 40, 34, 27, 19, 10, 76, 65, 63, 60, 56, 51, 45, 38, 30, 21, 11
Offset: 1

Views

Author

Gary W. Adamson, Jul 18 2007

Keywords

Comments

Left column = A034856: (1, 4, 8, 13, 19, 26, 34, ...). Row sums = A131820: (1, 6, 16, 33, 59, 96, ...).

Examples

			First few rows of the triangle:
   1;
   4,  2;
   8,  5,  3;
  13,  9,  7,  4;
  19, 14, 12,  9,  5;
  26, 20, 18, 15, 11,  6;
  34, 27, 25, 22, 18, 13,  7;
  ...
		

Crossrefs

Programs

  • PARI
    tabl(nn) = {m131818 = matrix(nn, nn, n, k, if (k==1, n, if (k <= n, k, 0))); m000012 = matrix(nn, nn, n, k, (k<=n)); m131819 = m131818 * m000012; for (n = 1, nn, for (k = 1, n, print1(m131819[n, k], ", ");););} \\ Michel Marcus, Feb 12 2014

Extensions

More terms from Michel Marcus, Feb 12 2014

A134225 A007436 + A134082 - A000012 as infinite lower triangular matrices; where A000012 = (1; 1,1; 1,1,1; ...).

Original entry on oeis.org

1, 3, 1, 2, 5, 1, 3, 2, 7, 1, 4, 3, 2, 9, 1, 5, 4, 3, 2, 11, 1, 6, 5, 4, 3, 2, 13, 1, 7, 6, 5, 4, 3, 2, 15, 1, 8, 7, 6, 5, 4, 3, 2, 17, 1, 9, 8, 7, 6, 5, 4, 3, 2, 19, 1
Offset: 1

Views

Author

Gary W. Adamson, Oct 14 2007

Keywords

Comments

Row sums = A034856: (1, 4, 8, 13, 19, 26, ...).

Examples

			First few rows of the triangle:
  1;
  3, 1;
  2, 5, 1;
  3, 2, 7, 1;
  4, 3, 2, 9,  1;
  5, 4, 3, 2, 11,  1;
  6, 5, 4, 3,  2, 13,  1;
  7, 6, 5, 4,  3,  2, 15, 1;
  ...
		

Crossrefs

A237124 Triangle of numbers related to Catalan numbers (A000108).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 3, 4, 3, 1, 9, 11, 8, 4, 1, 28, 33, 24, 13, 5, 1, 90, 104, 76, 43, 19, 6, 1, 297, 339, 249, 145, 69, 26, 7, 1, 1001, 1133, 836, 497, 248, 103, 34, 8, 1, 3432, 3861, 2860, 1727, 891, 394, 146, 43, 9, 1, 11934, 13364, 9932, 6071, 3211, 1484, 593, 199, 53, 10, 1
Offset: 0

Views

Author

Philippe Deléham, Feb 03 2014

Keywords

Comments

Riordan array (1 +x +x^2*C(x)^3, x*C(x)) where C(x) is the g.f. of A000108.
Diagonal sums are A000108(n).
Row sums are T(n+1,1).
T(n,0) = A071724(n-1).
T(n,1) = A220902(n), n>=2.
T(n,2) = A228404(n-2), n>=4.
T(n+3,3) = A033434(n).
T(n,n) = 1.
T(n+1,n) = n+1.
T(n+2,n) = A034856(n+1).

Examples

			Triangle begins:
      1;
      1,     1;
      1,     2,    1;
      3,     4,    3,    1;
      9,    11,    8,    4,    1;
     28,    33,   24,   13,    5,    1;
     90,   104,   76,   43,   19,    6,   1;
    297,   339,  249,  145,   69,   26,   7,   1;
   1001,  1133,  836,  497,  248,  103,  34,   8,  1;
   3432,  3861, 2860, 1727,  891,  394, 146,  43,  9,  1;
  11934, 13364, 9932, 6071, 3211, 1484, 593, 199, 53, 10, 1;
  ...
		

Crossrefs

Cf. A000108.

Programs

  • Mathematica
    b[n_, k_]:= Binomial[2*n-k+1, n-k];
    T[n_, k_]:= If[n<3, Binomial[n, k], b[n, k] -2*b[n, k+1] -b[n, k+2] +3*b[n, k+3] - 2*b[n, k+4]];
    Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, May 08 2021 *)
  • Sage
    def b(n,k): return binomial(2*n-k+1, n-k)
    def T(n,k): return binomial(n,k) if (n<3) else b(n,k) -2*b(n, k+1) -b(n, k+2) +3*b(n, k+3) -2*b(n, k+4)
    flatten([[T(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, May 08 2021

Formula

From Peter Bala, Feb 18 2018: (Start)
T(n,k) = C(2*n+1-k, n-k) - 2*C(2*n-k, n-k-1) - C(2*n-1-k, n-k-2) + 3*C(2*n-2-k, n-k-3) - 2*C(2*n-3-k, n-k-4), for n > 2, otherwise C(n, k).
The n-th row polynomial of the row reverse triangle equals the n-th degree Taylor polynomial of the function (1 - x^2 + x^3)*(1 - 2*x)/(1 - x)^2 * 1/(1 - x)^n about 0. For example, for n = 4, (1 - x^2 + x^3)*(1 - 2*x)/(1 - x)^2 * 1/(1 - x)^4 = 1 + 4*x + 8*x^2 + 11*x^3 + 9*x^4 + O(x^5), giving (9, 11, 8, 4, 1) as row 4. (End)

A237519 Triangle read by rows: T(n,k), n>=1, k>=1, in which column k lists the partial sums of the column k of A237273 starting in row k^2.

Original entry on oeis.org

1, 4, 8, 13, 2, 19, 2, 26, 7, 34, 7, 43, 13, 53, 13, 3, 64, 20, 3, 76, 20, 3, 89, 28, 10, 103, 28, 10, 118, 37, 10, 134, 37, 18, 151, 47, 18, 4, 169, 47, 18, 4, 188, 58, 27, 4, 208, 58, 27, 4, 229, 70, 27, 13, 251, 70, 37, 13, 274, 83, 37, 13, 298, 83, 37, 13, 323, 97, 48, 23, 349, 97, 48, 23, 5
Offset: 1

Views

Author

Omar E. Pol, Feb 08 2014

Keywords

Comments

The sum of row n is A024916(n), the sum of all divisors of all positive integers <= n.
Row n has length A000196(n).
Column 1 is A034856.
Column 2 lists the elements of A155212 repeated.
Column 3 lists the elements of A051938 repeated with three copies of every element.
Column k contains k copies of every element.

Examples

			Triangle begins:
1;
4;
8;
13,   2;
19,   2;
26,   7;
34,   7;
43,  13;
53,  13,  3;
64,  20,  3;
76,  20,  3;
89,  28, 10;
103, 28, 10;
118, 37, 10;
134, 37, 18;
151, 47, 18,  4;
169, 47, 18,  4;
188, 58, 27,  4;
208, 58, 27,  4;
229, 70, 27, 13;
251, 70, 37, 13;
274, 83, 37, 13;
298, 83, 37, 13;
323, 97, 48, 23;
349, 97, 48, 23,  5;
...
		

Crossrefs

A283054 Triangle read by rows: T(n,k) = T(n,k-1) + T(n-1,k), T(n,0)=1, T(n,n) = T(n,n-1) + 1.

Original entry on oeis.org

1, 1, 2, 1, 3, 4, 1, 4, 8, 9, 1, 5, 13, 22, 23, 1, 6, 19, 41, 64, 65, 1, 7, 26, 67, 131, 196, 197, 1, 8, 34, 101, 232, 428, 625, 626, 1, 9, 43, 144, 376, 804, 1429, 2055, 2056, 1, 10, 53, 197, 573, 1377, 2806, 4861, 6917, 6918, 1, 11, 64, 261, 834, 2211, 5017, 9878, 16795, 23713, 23714, 1, 12, 76, 337, 1171, 3382, 8399, 18277, 35072, 58785, 82499, 82500
Offset: 0

Views

Author

Ely Golden, Feb 27 2017

Keywords

Comments

The left diagonals form polynomial sequences. This is due to the observation that diagonal 0 D_0(x) = 1, and D_n(x) = D_n(x-1)+D_(n-1)(x+1), with D_n(-1) = 1 which is a recurrence that can be solved.
These polynomials begin 1, x+2, (x(x+7)+8)/2, (x(x(x+15)+62)+54)/6, (x(x(x(x+26)+227)+730)+552)/24, etc., the first 3 of which correspond to A000012(n), A000027(n+2), and A034856(n+2), respectively.
The rightmost diagonal appears to follow A014137(n). The second rightmost appears to follow A014138(n+1), the third appears to follow A001453(n+2), the fourth appears to follow A114277(n), and the fifth appears to follow A143955(n+3).
A closed-form formula for T(n,k) would be very desirable.

Examples

			First 7 rows:
  1;
  1,   2;
  1,   3,   4;
  1,   4,   8,   9;
  1,   5,  13,  22,  23;
  1,   6,  19,  41,  64,  65;
  1,   7,  26,  67, 131, 196, 197;
		

Programs

  • Mathematica
    T[0, 0] = 1; T[n_, k_] := T[n, k] = Which[k == 0, 1, k == n, T[n, n - 1] + 1, True, T[n, k - 1] + T[n - 1, k]]; Table[T[n, k], {n, 0, 11}, {k, 0, n}] // Flatten (* Michael De Vlieger, Feb 27 2017 *)
  • PARI
    T(n,k)=if(k==0,return(1));if(k==n,return(T(n,n-1)+1));T(n,k-1)+T(n-1,k)
    for(n=0,10,for(k=0,n,print1(T(n,k),", "))) \\ Derek Orr, Feb 28 2017
  • SageMath
    def sideTriangleAt(a,b):
        if(b==0): return 1
        elif(b==a): return sideTriangleAt(a,b-1)+1
        else: return sideTriangleAt(a,b-1)+sideTriangleAt(a-1,b)
    def sideTriangle(size):
        li=[]
        for c in range(size):
            for d in range(c+1):
                if(d==0): li.append([1])
                elif(d==c): li[c].append(li[c][d-1]+1)
                else: li[c].append(li[c][d-1]+li[c-1][d])
        return li
    trig=sideTriangle(125)
    for c in range(len(trig)):
        print(str(trig[c])[1:-1].replace(",",""))
    

A303273 Array T(n,k) = binomial(n, 2) + k*n + 1 read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 4, 4, 1, 4, 6, 7, 7, 1, 5, 8, 10, 11, 11, 1, 6, 10, 13, 15, 16, 16, 1, 7, 12, 16, 19, 21, 22, 22, 1, 8, 14, 19, 23, 26, 28, 29, 29, 1, 9, 16, 22, 27, 31, 34, 36, 37, 37, 1, 10, 18, 25, 31, 36, 40, 43, 45, 46, 46, 1, 11, 20, 28, 35, 41
Offset: 0

Views

Author

Keywords

Comments

Columns are linear recurrence sequences with signature (3,-3,1).
8*T(n,k) + A166147(k-1) are squares.
Columns k are binomial transforms of [1, k, 1, 0, 0, 0, ...].
Antidiagonals sums yield A116731.

Examples

			The array T(n,k) begins
1    1    1    1    1    1    1    1    1    1    1    1    1  ...  A000012
1    2    3    4    5    6    7    8    9   10   11   12   13  ...  A000027
2    4    6    8   10   12   14   16   18   20   22   24   26  ...  A005843
4    7   10   13   16   19   22   25   28   31   34   37   40  ...  A016777
7   11   15   19   23   27   31   35   39   43   47   51   55  ...  A004767
11  16   21   26   31   36   41   46   51   56   61   66   71  ...  A016861
16  22   28   34   40   46   52   58   64   70   76   82   88  ...  A016957
22  29   36   43   50   57   64   71   78   85   92   99  106  ...  A016993
29  37   45   53   61   69   77   85   93  101  109  117  125  ...  A004770
37  46   55   64   73   82   91  100  109  118  127  136  145  ...  A017173
46  56   66   76   86   96  106  116  126  136  146  156  166  ...  A017341
56  67   78   89  100  111  122  133  144  155  166  177  188  ...  A017401
67  79   91  103  115  127  139  151  163  175  187  199  211  ...  A017605
79  92  105  118  131  144  157  170  183  196  209  222  235  ...  A190991
...
The inverse binomial transforms of the columns are
1    1    1    1    1    1    1    1    1    1    1    1    1  ...
0    1    2    3    4    5    6    7    8    9   10   11   12  ...
1    1    1    1    1    1    1    1    1    1    1    1    1  ...
0    0    0    0    0    0    0    0    0    0    0    0    0  ...
0    0    0    0    0    0    0    0    0    0    0    0    0  ...
0    0    0    0    0    0    0    0    0    0    0    0    0  ...
...
T(k,n-k) = A087401(n,k) + 1 as triangle
1
1   1
1   2   2
1   3   4   4
1   4   6   7   7
1   5   8  10  11  11
1   6  10  13  15  16  16
1   7  12  16  19  21  22  22
1   8  14  19  23  26  28  29  29
1   9  16  22  27  31  34  36  37  37
1  10  18  25  31  36  40  43  45  46  46
...
		

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics: A Foundation for Computer Science, Addison-Wesley, 1994.

Crossrefs

Programs

  • Maple
    T := (n, k) -> binomial(n, 2) + k*n + 1;
    for n from 0 to 20 do seq(T(n, k), k = 0 .. 20) od;
  • Mathematica
    Table[With[{n = m - k}, Binomial[n, 2] + k n + 1], {m, 0, 11}, {k, m, 0, -1}] // Flatten (* Michael De Vlieger, Apr 21 2018 *)
  • Maxima
    T(n, k) := binomial(n, 2)+ k*n + 1$
    for n:0 thru 20 do
        print(makelist(T(n, k), k, 0, 20));
    
  • PARI
    T(n,k) = binomial(n, 2) + k*n + 1;
    tabl(nn) = for (n=0, nn, for (k=0, nn, print1(T(n, k), ", ")); print); \\ Michel Marcus, May 17 2018

Formula

G.f.: (3*x^2*y - 3*x*y + y - 2*x^2 + 2*x - 1)/((x - 1)^3*(y - 1)^2).
E.g.f.: (1/2)*(2*x*y + x^2 + 2)*exp(y + x).
T(n,k) = 3*T(n-1,k) - 3*T(n-2,k) + T(n-3,k), with T(0,k) = 1, T(1,k) = k + 1 and T(2,k) = 2*k + 2.
T(n,k) = T(n-1,k) + n + k - 1.
T(n,k) = T(n,k-1) + n, with T(n,0) = 1.
T(n,0) = A152947(n+1).
T(n,1) = A000124(n).
T(n,2) = A000217(n).
T(n,3) = A034856(n+1).
T(n,4) = A052905(n).
T(n,5) = A051936(n+4).
T(n,6) = A246172(n+1).
T(n,7) = A302537(n).
T(n,8) = A056121(n+1) + 1.
T(n,9) = A056126(n+1) + 1.
T(n,10) = A051942(n+10) + 1, n > 0.
T(n,11) = A101859(n) + 1.
T(n,12) = A132754(n+1) + 1.
T(n,13) = A132755(n+1) + 1.
T(n,14) = A132756(n+1) + 1.
T(n,15) = A132757(n+1) + 1.
T(n,16) = A132758(n+1) + 1.
T(n,17) = A212427(n+1) + 1.
T(n,18) = A212428(n+1) + 1.
T(n,n) = A143689(n) = A300192(n,2).
T(n,n+1) = A104249(n).
T(n,n+2) = T(n+1,n) = A005448(n+1).
T(n,n+3) = A000326(n+1).
T(n,n+4) = A095794(n+1).
T(n,n+5) = A133694(n+1).
T(n+2,n) = A005449(n+1).
T(n+3,n) = A115067(n+2).
T(n+4,n) = A133694(n+2).
T(2*n,n) = A054556(n+1).
T(2*n,n+1) = A054567(n+1).
T(2*n,n+2) = A033951(n).
T(2*n,n+3) = A001107(n+1).
T(2*n,n+4) = A186353(4*n+1) (conjectured).
T(2*n,n+5) = A184103(8*n+1) (conjectured).
T(2*n,n+6) = A250657(n-1) = A250656(3,n-1), n > 1.
T(n,2*n) = A140066(n+1).
T(n+1,2*n) = A005891(n).
T(n+2,2*n) = A249013(5*n+4) (conjectured).
T(n+3,2*n) = A186384(5*n+3) = A186386(5*n+3) (conjectured).
T(2*n,2*n) = A143689(2*n).
T(2*n+1,2*n+1) = A143689(2*n+1) (= A030503(3*n+3) (conjectured)).
T(2*n,2*n+1) = A104249(2*n) = A093918(2*n+2) = A131355(4*n+1) (= A030503(3*n+5) (conjectured)).
T(2*n+1,2*n) = A085473(n).
a(n+1,5*n+1)=A051865(n+1) + 1.
a(n,2*n+1) = A116668(n).
a(2*n+1,n) = A054569(n+1).
T(3*n,n) = A025742(3*n-1), n > 1 (conjectured).
T(n,3*n) = A140063(n+1).
T(n+1,3*n) = A069099(n+1).
T(n,4*n) = A276819(n).
T(4*n,n) = A154106(n-1), n > 0.
T(2^n,2) = A028401(n+2).
T(1,n)*T(n,1) = A006000(n).
T(n*(n+1),n) = A211905(n+1), n > 0 (conjectured).
T(n*(n+1)+1,n) = A294259(n+1).
T(n,n^2+1) = A081423(n).
T(n,A000217(n)) = A158842(n), n > 0.
T(n,A152947(n+1)) = A060354(n+1).
floor(T(n,n/2)) = A267682(n) (conjectured).
floor(T(n,n/3)) = A025742(n-1), n > 0 (conjectured).
floor(T(n,n/4)) = A263807(n-1), n > 0 (conjectured).
ceiling(T(n,2^n)/n) = A134522(n), n > 0 (conjectured).
ceiling(T(n,n/2+n)/n) = A051755(n+1) (conjectured).
floor(T(n,n)/n) = A133223(n), n > 0 (conjectured).
ceiling(T(n,n)/n) = A007494(n), n > 0.
ceiling(T(n,n^2)/n) = A171769(n), n > 0.
ceiling(T(2*n,n^2)/n) = A046092(n), n > 0.
ceiling(T(2*n,2^n)/n) = A131520(n+2), n > 0.
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