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 1-10 of 14 results. Next

A007042 Left diagonal of partition triangle A047812.

Original entry on oeis.org

0, 1, 3, 5, 9, 13, 20, 28, 40, 54, 75, 99, 133, 174, 229, 295, 383, 488, 625, 790, 1000, 1253, 1573, 1956, 2434, 3008, 3716, 4563, 5602, 6840, 8347, 10141, 12308, 14881, 17975, 21635, 26013, 31183, 37336, 44581, 53172, 63259, 75173, 89132, 105556, 124752
Offset: 1

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Author

Keywords

Comments

For n > 2, a(n) is also the number of partitions of n into parts <= n-2: a(n) = A026820(n+1, n-1). - Reinhard Zumkeller, Jan 21 2010
Also, the number of partitions of 2*n in which n-1 is the maximal part; see the Mathematica section. - Clark Kimberling, Mar 13 2012
This is column 2 of the matrix A in Sect. 2.3 of the Govindarajan preprint, cf. references and A096651. - M. F. Hasler, Apr 12 2012

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Julia
    using Nemo
    function A007042List(len)
        R, z = PolynomialRing(ZZ, "z")
        e = eta_qexp(-1, len+2, z)
        [coeff(e, j) - 2 for j in 2:len+1] end
    A007042List(45) |> println # Peter Luschny, May 30 2020
  • Mathematica
    f[n_]:= Length[Select[IntegerPartitions[2 n], First[#]==n-1 &]]; Table[f[n], {n, 1, 24}] (* Clark Kimberling, Mar 13 2012 *)
    a[n_]:= PartitionsP[n+1]-2; Table[a[n], {n,1,50}] (* Jean-François Alcover, Jan 28 2015, after M. F. Hasler *)
  • PARI
    A007042(n)=numbpart(n+1)-2  \\ M. F. Hasler, Apr 12 2012
    

Formula

a(n) = A000041(n+1) - 2. - Vladeta Jovovic, Oct 06 2001

Extensions

More terms from James Sellers
Name edited by Petros Hadjicostas, May 31 2020

A007044 Left diagonal of partition triangle A047812.

Original entry on oeis.org

0, 0, 1, 7, 20, 48, 100, 194, 352, 615, 1034, 1693, 2705, 4239, 6522, 9889, 14786, 21844, 31913, 46165, 66162, 94035, 132600, 185637, 258128, 356674, 489906, 669173, 909212, 1229217, 1653993, 2215597, 2955192, 3925659, 5194520, 6847963, 8995524, 11776227
Offset: 1

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Author

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t) option remember; `if`(n=0, 1, `if`(n<0
          or t*i b(2*n+2, n$2):
    seq(a(n), n=1..50);  # Alois P. Heinz, May 31 2020
  • Mathematica
    b[n_, i_, t_] := b[n, i, t] = If[n == 0, 1, If[n < 0 || t i < n, 0, b[n, i - 1, t] + b[n - i, Min[i, n - i], t - 1]]];
    a[n_] := b[2n+2, n, n];
    Array[a, 50] (* Jean-François Alcover, Nov 23 2020, after Alois P. Heinz *)
  • PARI
    T(n, k) = polcoeff(prod(j=0, n-1, (1-q^(2*n-j))/(1-q^(j+1)) ), k*(n+1) );
    for(n=1, 40, print1(T(n, 2), ",")) \\ Petros Hadjicostas, May 31 2020

Extensions

Name edited by Petros Hadjicostas, May 31 2020

A007045 Second (lower) diagonal of partition triangle A047812.

Original entry on oeis.org

0, 1, 5, 20, 51, 112, 221, 411, 720, 1221, 2003, 3206, 5021, 7728, 11698, 17472, 25766, 37580, 54254, 77617, 110087, 154942, 216488, 300456, 414365, 568113, 774571, 1050572, 1417868, 1904641, 2547152, 3392042, 4498948, 5944158, 7824703, 10263932, 13418043, 17484554
Offset: 2

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Author

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t) option remember; `if`(n=0, 1, `if`(n<0
          or t*i b((n-3)*(n+1), n$2):
    seq(a(n), n=2..40);  # Alois P. Heinz, May 31 2020
  • Mathematica
    s[n_] := s[n] = Series[Product[(1 - q^(2*n - k))/(1 - q^(k + 1)), {k, 0, n - 1}], {q, 0, n^2}]; t[n_, k_] := SeriesCoefficient[s[n], k*(n + 1)]; A007045 = Join[{0}, Table[t[n + 3, n], {n, 0, 25}] ] (* Jean-François Alcover, Apr 25 2012 *)
  • PARI
    T(n, k) = polcoeff(prod(j=0, n-1, (1-q^(2*n-j))/(1-q^(j+1)) ), k*(n+1) );
    for(n=3, 33, print1(T(n, n-3), ", ")) \\ Petros Hadjicostas, May 31 2020

A136621 Transpose T(n,k) of Parker's partition triangle A047812 (n >= 1 and 0 <= k <= n-1).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 7, 5, 1, 1, 11, 20, 9, 1, 1, 18, 51, 48, 13, 1, 1, 26, 112, 169, 100, 20, 1, 1, 38, 221, 486, 461, 194, 28, 1, 1, 52, 411, 1210, 1667, 1128, 352, 40, 1, 1, 73, 720, 2761, 5095, 4959, 2517, 615, 54, 1, 1, 97, 1221, 5850, 13894, 18084, 13241, 5288, 1034, 75, 1
Offset: 1

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Author

Alford Arnold, Jan 26 2008

Keywords

Comments

Parker's triangle is closely associated with q-binomial coefficients and Gaussian polynomials; cf. A063746. For example, row 4 of A063746 is 1, 1, 2, 3, 5, 5, 7, 7, 8, 7, 7, 5, 5, 3, 2, 1, 1, the coefficients of [8, 4], while the entries in row 4 of A047812 are the coefficients of q^(k*(4+1)) = q^(5*k) in [8, 4] where k runs from 0 to n-1 = 3. Likewise, by symmetry, "1 7 5 1" is embedded also because they are the coefficients of q^(5*(3-k)), where k runs from 0 to n-1 = 3. [Edited by Petros Hadjicostas, May 30 2020]

Examples

			Row four of A047812 is 1 5 7 1, so row four of the present entry is 1 7 5 1.
From _Petros Hadjicostas_, May 30 2020: (Start)
Triangle T(n,k) (with rows n >= 1 and columns k = 0..n-1) begins:
  1;
  1,  1;
  1,  3,   1;
  1,  7,   5,    1;
  1, 11,  20,    9,    1;
  1, 18,  51,   48,   13,    1;
  1, 26, 112,  169,  100,   20,   1;
  1, 38, 221,  486,  461,  194,  28,  1;
  1, 52, 411, 1210, 1667, 1128, 352, 40, 1;
  ... (End)
		

Crossrefs

Cf. A000108 (Catalan row sums), A047812, A063746.

Programs

  • Maple
    b:= proc(n, i, t) option remember; `if`(n=0, 1, `if`(t*i
           b((n-k-1)*(n+1), n$2):
    seq(seq(T(n, k), k=0..n-1), n=1..12);  # Alois P. Heinz, May 30 2020
  • Mathematica
    T[n_, k_]:= SeriesCoefficient[QBinomial[2*n, n, q], {q, 0, k*(n+1)}];
    Table[T[n, n-k], {n,12}, {k,n}]//Flatten (* G. C. Greubel, May 31 2020 *)
    b[n_, i_, t_] := b[n, i, t] = If[n == 0, 1, If[n < 0 || t i < n, 0, b[n, i - 1, t] + b[n - i, Min[i, n - i], t - 1]]];
    T[n_, k_] := b[(n-k-1)(n+1), n, n];
    Table[T[n, k], {n, 1, 12}, {k, 0, n-1}] // Flatten (* Jean-François Alcover, Nov 27 2020, after Alois P. Heinz *)
  • PARI
    T(n, k) = #partitions(k*(n+1), n, n);
    for (n=1, 10, for (k=0, n-1, print1(T(n, n-1-k), ", "); ); print(); ); \\ Petros Hadjicostas, May 30 2020
    /* Second program, courtesy of G. C. Greubel */
    T(n,k) = polcoeff(prod(j=0, n-1, (1-q^(2*n-j))/(1-q^(j+1)) ), k*(n+1) );
    vector(12, n, vector(n, k, T(n,n-k))) \\ Petros Hadjicostas, May 31 2020
    
  • Sage
    def T(n,k):
        P. = PowerSeriesRing(ZZ, k*(n+1)+1)
        return P( q_binomial(2*n, n, x) ).list()[k*(n+1)]
    [[ T(n,n-k) for k in (1..n)] for n in (1..12)] # G. C. Greubel, May 31 2020

Extensions

Name edited by Petros Hadjicostas, May 30 2020

A128567 Matrix square, T(n,k), of Parker's partition triangle A047812, read by rows (n >= 1 and 0 <= k <= n-1).

Original entry on oeis.org

1, 2, 1, 5, 6, 1, 14, 31, 14, 1, 42, 133, 117, 22, 1, 132, 587, 813, 300, 36, 1, 429, 2531, 4871, 2896, 692, 52, 1, 1430, 10950, 27743, 23961, 9206, 1430, 76, 1, 4862, 47185, 151208, 175734, 96418, 24598, 2798, 104, 1, 16796, 203704, 804065, 1200301, 882471, 329426, 62885, 5236, 146, 1
Offset: 1

Views

Author

Paul D. Hanna, Mar 12 2007

Keywords

Comments

Column 0 is the Catalan numbers (A000108). Parker's partition triangle may be defined as: A047812(n,k) = [q^(n*k+k)] in the central q-binomial coefficient [2*n,n] for n >= 1 and 0 <= k <= n-1. [Edited by Petros Hadjicostas, May 30 2020]

Examples

			Triangle T(n,k) (with rows n >= 1 and columns k = 0..n-1) begins:
      1;
      2,      1;
      5,      6,      1;
     14,     31,     14,       1;
     42,    133,    117,      22,      1;
    132,    587,    813,     300,     36,      1;
    429,   2531,   4871,    2896,    692,     52,     1;
   1430,  10950,  27743,   23961,   9206,   1430,    76,    1;
   4862,  47185, 151208,  175734,  96418,  24598,  2798,  104,   1;
  16796, 203704, 804065, 1200301, 882471, 329426, 62885, 5236, 146, 1;
  ...
		

Crossrefs

Cf. A000108 (column k=0), A047812, A128568 (column k=1), A128569 (column k=2), A128602 (row sums).

Programs

  • PARI
    {T(n, k)=local(M);M=matrix(n+1,n+1,r,c,if(rPetros Hadjicostas, May 31 2020

Formula

T(n,k) = Sum_{s=k..n-1} A047812(n,s)*A047812(s+1,k) for n >= 1 and 0 <= k <= n-1. - Petros Hadjicostas, May 31 2020

Extensions

Name edited and offset changed by Petros Hadjicostas, May 30 2020

A137614 Triangle read by rows: A000012 * A047812 as infinite lower triangular matrices.

Original entry on oeis.org

1, 2, 1, 3, 4, 1, 4, 9, 8, 1, 5, 18, 28, 12, 1, 6, 31, 76, 63, 19, 1, 7, 51, 176, 232, 131, 27, 1, 8, 79, 370, 693, 617, 248, 39, 1, 9, 119, 722, 1821, 2284, 1458, 450, 53, 1, 10, 173, 1337, 4338, 7243, 6553, 3211, 773, 74, 1
Offset: 0

Views

Author

Gary W. Adamson, Jan 30 2008

Keywords

Comments

Row sums = A014138: (1, 3, 8, 22, 64, 196, 625, ...).
From Petros Hadjicostas, Jun 01 2020: (Start)
We prove the claim above. From Guy (1992, 1993), we know that A000108(n) = Sum_{k=0..n-1} A047812(k) (the row sums of Parker's triangle are Catalan numbers).
We then have Sum_{k=0..n-1} T(n,k) = Sum_{k=0..n-1} Sum_{s=k+1..n} A047812(s,k) = Sum_{s=1..n} Sum_{k=0..s-1} A047812(s,k) = Sum_{s=1..n} A000108(s) = A014138(n) because A014138 contains partial sums of the Catalan numbers. (End)

Examples

			Triangle T(n,k) (with rows n >= 1 and columns k = 0..n-1) begins:
  1;
  2,  1;
  3,  4,   1;
  4,  9,   8,   1;
  5, 18,  28,  12,   1;
  6, 31,  76,  63,  19,  1;
  7, 51, 176, 232, 131, 27, 1;
  ...
		

Crossrefs

Programs

  • PARI
    A(n, k) = polcoeff(prod(j=0, n-1, (1-q^(2*n-j))/(1-q^(j+1)) ), k*(n+1) );
    T(n,k) = sum(s=k+1, n, A(s,k));
    vector(15, n, vector(n, k, T(n, k-1))) \\ Petros Hadjicostas, Jun 01 2020

Formula

T(n,k) = Sum_{s=k+1..n} A047812(s,k) for n >= 1 and 0 <= k <= n-1. - Petros Hadjicostas, Jun 01 2020

A335323 First lower diagonal of Parker's triangle A047812.

Original entry on oeis.org

0, 1, 3, 7, 11, 18, 26, 38, 52, 73, 97, 131, 172, 227, 293, 381, 486, 623, 788, 998, 1251, 1571, 1954, 2432, 3006, 3714, 4561, 5600, 6838, 8345, 10139, 12306, 14879, 17973, 21633, 26011, 31181, 37334, 44579, 53170, 63257, 75171, 89130, 105554, 124750, 147269
Offset: 1

Views

Author

Petros Hadjicostas, May 31 2020

Keywords

Comments

Apparently, this sequence was originally intended to be A7043 (now A007043), but for some reason it was crossed out on p. 4 of the annotated copy of Guy's 1992 preprint.
a(n) is the number of partitions of (n-2)*(n+1) into at most n parts each no bigger than n. Thus, a(n) is the coefficient of q^((n-2)*(n+1)) in the q-binomial coefficient [2*n, n].

Examples

			a(1) = 0 because it does not make sense to talk about the partitions of (1-2)*(1+1) = -2.
a(2) = 1 because we have only the empty partition for (2-2)*(2+1) = 0.
a(3) = 3 because we have the following partitions of (3-2)*(3+1) = 4 into no more than 3 parts each no bigger than 3: 1+3 = 1+1+2 = 2+2.
a(4) = 7 because we have the following partitions of (4-2)*(4+1) = 10 into no more than 4 parts each no bigger than 4: 2+4+4 = 3+3+4 = 1+1+4+4 = 1+2+3+4 = 1+3+3+3 = 2+2+2+4 = 2+2+3+3.
The PARI function partitions((n-2)*(n+1), n, n) can generate these partitions.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t) option remember; `if`(n=0, 1, `if`(n<0
          or t*i b((n-2)*(n+1), n$2):
    seq(a(n), n=1..50);  # Alois P. Heinz, May 31 2020
  • Mathematica
    b[n_, i_, t_] := b[n, i, t] = If[n == 0, 1, If[n < 0 || t i < n, 0, b[n, i - 1, t] + b[n - i, Min[i, n - i], t - 1]]];
    a[n_] := b[(n-2)(n+1), n, n];
    Array[a, 50] (* Jean-François Alcover, Nov 27 2020, after Alois P. Heinz *)
  • PARI
    T(n, k) = polcoeff(prod(j=0, n-1, (1-q^(2*n-j))/(1-q^(j+1)) ), k*(n+1) );
    for(n=1, 43, print1(T(n, n-2), ", "))

A128545 Triangle, read by rows, where T(n,k) is the coefficient of q^(n*k) in the q-binomial coefficient [2*n, n] for n >= k >= 0.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 5, 8, 5, 1, 1, 7, 18, 18, 7, 1, 1, 11, 39, 58, 39, 11, 1, 1, 15, 75, 155, 155, 75, 15, 1, 1, 22, 141, 383, 526, 383, 141, 22, 1, 1, 30, 251, 867, 1555, 1555, 867, 251, 30, 1, 1, 42, 433, 1860, 4192, 5448, 4192, 1860, 433, 42, 1
Offset: 0

Views

Author

Paul D. Hanna, Mar 10 2007

Keywords

Comments

Variant of A047812 (Parker's partition triangle).
Column 1 equals the number of partitions of n: A000041(n) is the coefficient of q^n in the central q-binomial coefficient [2*n, n] for n > 0.

Examples

			Triangle T(n,k) (with rows n >= 0 and columns k = 0..n) begins:
  1;
  1,  1;
  1,  2,   1;
  1,  3,   3,    1;
  1,  5,   8,    5,    1;
  1,  7,  18,   18,    7,    1;
  1, 11,  39,   58,   39,   11,    1;
  1, 15,  75,  155,  155,   75,   15,    1;
  1, 22, 141,  383,  526,  383,  141,   22,   1;
  1, 30, 251,  867, 1555, 1555,  867,  251,  30,  1;
  1, 42, 433, 1860, 4192, 5448, 4192, 1860, 433, 42, 1;
  ...
		

Crossrefs

Cf. A003239, A047812 (variant), A047996, A123610, A123611 (row sums).
Cf. A000041 (column 1), A128552 (column 2), A128553 (column 3), A128554 (column 4).

Programs

  • PARI
    T(n,k)=if(n
    				

Formula

Row sums equal the row sums of triangle A123610: A123611(n) = 2*A047996(2*n,n) = 2*A003239(n) for n > 0, where A047996 is the triangle of circular binomial coefficients and A003239(n) = number of rooted planar trees with n non-root nodes.

A051643 Central elements in Parker's partition triangle.

Original entry on oeis.org

1, 3, 20, 169, 1667, 18084, 208960, 2527074, 31630390, 406680465, 5342750699, 71442850111, 969548468960, 13323571588607, 185072895183632, 2594890728951909, 36681505784903758, 522291180086851188, 7484621370716999785, 107876522368295972285, 1562916545414144667559
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, t) option remember; `if`(n=0, 1, `if`(t*i
           b(2*n*(n+1), 2*n+1$2):
    seq(a(n), n=0..20);  # Alois P. Heinz, May 30 2020
  • Mathematica
    a[n_] := SeriesCoefficient[QBinomial[2(2n+1), 2n+1, q], {q, 0, 2n(n+1)}];
    Table[a[n], {n, 0, 17}] (* Jean-François Alcover, Aug 19 2019 *)

Formula

a(n) = coefficient of q^((m^2-1)/2) = q(2*n*(n+1)) in the q-binomial coefficient [2*m, m] = [2*(2*n+1), 2*n+1], where m = 2*n+1. [Corrected by Petros Hadjicostas, May 30 2020]
a(n) is the number of partitions of 2*n*(n+1) into at most 2*n+1 parts each no bigger than 2*n+1. - Petros Hadjicostas, May 30 2020

Extensions

a(18)-a(20) from Alois P. Heinz, May 30 2020

A081719 Triangle T(n,k) read by rows, related to Faà di Bruno's formula (n >= 0 and 0 <= k <= n).

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 5, 5, 1, 0, 1, 9, 14, 7, 1, 0, 1, 13, 32, 27, 9, 1, 0, 1, 20, 66, 80, 44, 11, 1, 0, 1, 28, 123, 203, 160, 65, 13, 1, 0, 1, 40, 222, 465, 486, 280, 90, 15, 1, 0, 1, 54, 377, 985, 1305, 990, 448, 119, 17, 1, 0, 1, 75, 630, 1978, 3203, 3051, 1807, 672, 152, 19, 1
Offset: 0

Views

Author

N. J. A. Sloane, Apr 05 2003

Keywords

Comments

From Petros Hadjicostas, May 30 2020: (Start)
We may prove Philippe Deléham's formula by induction on n. Let P(n,k) = A008284(n,k) and b(n) = A039809(n). For n = 0, Sum_{k=0..0} T(0,k) = 1 = b(1). Let n >= 1, and assume his formula is true for all s < n, i.e., Sum_{k=0..s} T(s,k) = b(s+1).
Then Sum_{k=0..n} T(n, k) = Sum_{k=1..n} T(n,k) = Sum_{k=1..n} Sum_{s=k-1..n-1} P(n+1, s+1)*T(s, k-1) = Sum_{s=0..n-1} P(n+1, s+1) Sum_{k=1..s+1} T(s, k-1) = Sum_{s=0..n-1} P(n+1, s+1) Sum_{m=0..s} T(s,m) = Sum_{s=0..n-1} P(n+1, s+1)*b(s+1) = Sum_{r=1..n} P(n+1, r)*b(r) = b(n+1) (by the definition of b = A039809). (End)

Examples

			Triangle T(n,k) (with rows n >= 0 and columns k = 0..n) begins:
  1;
  0, 1;
  0, 1,  1;
  0, 1,  3,  1;
  0, 1,  5,  5,  1;
  0, 1,  9, 14,  7,  1;
  0, 1, 13, 32, 27,  9,  1;
  0, 1, 20, 66, 80, 44, 11, 1;
  ...
		

Crossrefs

Programs

  • Mathematica
    (* b = A008284 *)
    b[n_, k_]:= b[n, k]= If[n>0 && k>0, b[n-1, k-1] + b[n-k, k], Boole[n==0 && k==0]];
    T[n_, k_]:= T[n, k]= If[n==0 && k==0, 1, If[k==0, 0,  Sum[T[j, k-1]*b[n+1, j+1], {j, k-1, n-1}] ]];
    Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, May 31 2020 *)
  • PARI
    P(n, k)=#partitions(n-k, k); /* A008284 */
    tabl(nn) = {A = matrix(nn, nn, n, k, 0); A[1,1] = 1; for(n=2, nn, for(k=2, n, A[n,k] = sum(s=k-2, n-2, P(n, s+1)*A[s+1,k-1])));
    for (n=1, nn, for (k=1, n, print1(A[n, k], ", "); ); print(); ); }  \\ Petros Hadjicostas, May 29 2020

Formula

There is a recurrence involving the partition function A008284.
Sum_{k=0..n} T(n,k) = A039809(n+1). - Philippe Deléham, Sep 30 2006
From Petros Hadjicostas, May 30 2020: (Start)
T(n, k) = Sum_{s=k-1..n-1} A008284(n+1, s+1)*T(s, k-1) for 1 <= k <= n with T(0,0) = 1 and T(n,0) = 0 for n >= 1.
T(n, k=2) = A007042(n) = A047812(n,2). (End)

Extensions

More terms from Emeric Deutsch, Feb 28 2005
Showing 1-10 of 14 results. Next