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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A336633 Triangle read by rows: T(n,k) is the number of generalized permutations related to the degenerate Eulerian numbers with exactly k ascents (0 <= k <= max(0,n-1)).

Original entry on oeis.org

1, 1, 2, 2, 6, 16, 6, 24, 116, 116, 24, 120, 888, 1624, 888, 120, 720, 7416, 20984, 20984, 7416, 720, 5040, 67968, 270432, 419680, 270432, 67968, 5040, 40320, 682272, 3587904, 7861664, 7861664, 3587904, 682272, 40320, 362880, 7467840, 49701024, 144570624, 204403264, 144570624
Offset: 0

Views

Author

Orli Herscovici, Jul 28 2020

Keywords

Examples

			Triangle T(n,k) (with rows n >= 0 and columns k = 0..max(0,n-1)) begins:
     1;
     1;
     2,     2;
     6,    16,      6;
    24,   116,    116,     24;
   120,   888,   1624,    888,    120;
   720,  7416,  20984,  20984,   7416,   720;
  5040, 67968, 270432, 419680, 270432, 67968, 5040;
  ...
		

Crossrefs

Columns k = 0..1 give: A000142, A288964. Row sums give A007559.

Programs

  • Maple
    Tnk[0, 0] := 1; for n to N do
        for k from 0 to n do if 0 < k and k < n then Tnk[n, k] := (n + k)*Tnk[n - 1, k] + (2*n - k - 1)*Tnk[n - 1, k - 1]; else if k = 0 then Tnk[n, k] := (n + k)*Tnk[n - 1, k]; else Tnk[n, k] := 0; end if; end if; end do;
    end do

Formula

T(n,k) = (n+k)*T(n-1,k) + (2*n-k-1)*T(n-1,k-1) for positive integers n and 0 <= k < n; T(0,0)=1 (or T(1,0)=1); otherwise T(n,k)=0.
From Peter Bala, Jan 08 2021: (Start)
The following remarks are all conjectures:
The e.g.f. (without the initial 1) A(x,t) = x + (2 + 2*t)*x^2/2! + (6 + 16*t + 6*t^2)*x^3/3! + ... satisfies the autonomous differential equation dA/dx = (1 + A)^2*(1 + t*A)^2.
The series reversion of A(x,t) with respect to x equals Integral_{u = 0..x} 1/((1 + u)^2*(1 + t*u)^2) du.
Let f(x,t) = (1 + x)^2*(1 + t*x)^2 and let D be the operator f(x,t)*d/dx. Then the (n+1)-th row polynomial = D^n(f(x,t)) evaluated at x = 0. (End)

A341111 T(n, k) = [x^k] M(n)*Sum_{k=0..n} E2(n, k)*binomial(-x + n - k, 2*n), where E2 are the second-order Eulerian numbers A340556 and M(n) are the Minkowski numbers A053657. Triangle read by rows, T(n, k) for n >= 0 and 0 <= k <= 2*n+1.

Original entry on oeis.org

1, 0, 1, 1, 0, 10, 21, 14, 3, 0, 36, 96, 97, 47, 11, 1, 0, 12048, 36740, 45420, 29855, 11352, 2510, 300, 15, 0, 91200, 304480, 427348, 334620, 162255, 50787, 10302, 1310, 95, 3, 0, 109941120, 392583744, 603023624, 531477324, 300731214, 115291701, 30675678, 5682033, 719866, 59535, 2898, 63
Offset: 0

Views

Author

Peter Luschny, Feb 05 2021

Keywords

Examples

			Triangle starts:
[0] 1;
[1] 0, 1,     1;
[2] 0, 10,    21,     14,     3;
[3] 0, 36,    96,     97,     47,     11,     1;
[4] 0, 12048, 36740,  45420,  29855,  11352,  2510,  300,   15;
[5] 0, 91200, 304480, 427348, 334620, 162255, 50787, 10302, 1310, 95, 3.
		

Crossrefs

Programs

  • Maple
    E2 := (n, k) -> `if`(k=0, k^n, combinat:-eulerian2(n, k-1)):
    CoeffList := p -> [op(PolynomialTools:-CoefficientList(p, x))]:
    mser := series((y/(exp(y)-1))^x, y, 29): m := n -> denom(coeff(mser, y, n)):
    poly := n -> expand(m(n)*add(E2(n, k)*binomial(-x+n-k, 2*n), k = 0..n)):
    for n from 0 to 6 do CoeffList(poly(n)) od;
  • PARI
    M(n) = prod(i=1, #factor(n!)~, prime(i)^sum(k=0, #binary(n), floor((n-1)/((prime(i)-1)*prime(i)^k)))) \\ from A053657
    rows_upto(n) = my(v1, v2); v1 = vector(n, i, 0); v2 = vector(n+1, i, 0); v2[1] = 1; for(i=1, n, v1[i] = (i+x)*(i+x-1)/2*v2[i]; for(j=1, i-1, v1[j] *= (i-j)*(i+x)/(i-j+2)); v2[i+1] = vecsum(v1)/i); v2 = vector(n+1, i, M(i)*Vecrev(v2[i])) \\ Mikhail Kurkov, Aug 27 2025

A102147 Second Eulerian transform of 1, 2, 3, 4, 5, ... (A000027).

Original entry on oeis.org

1, 1, 5, 35, 315, 3465, 45045, 675675, 11486475, 218243025, 4583103525, 105411381075, 2635284526875, 71152682225625, 2063427784543125, 63966261320836875, 2110886623587616875, 73881031825566590625
Offset: 1

Views

Author

Ross La Haye, Feb 14 2005

Keywords

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, p. 256.

Crossrefs

Apparently equals A051577(n-2), n > 1.

Formula

a(n) = Sum_{k=0..n} E(n,k) A000027(k), where E(n,k) is a second-order Eulerian number (A008517).

A156184 A generalized recursion triangle sequence : m=1; t(n,k)=(k + m - 1)*t(n - 1, k, m) + (m*n - k + 1 - m)*t(n - 1, k - 1, m).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 4, 1, 1, 7, 16, 7, 1, 1, 11, 53, 53, 11, 1, 1, 16, 150, 318, 150, 16, 1, 1, 22, 380, 1554, 1554, 380, 22, 1, 1, 29, 892, 6562, 12432, 6562, 892, 29, 1, 1, 37, 1987, 25038, 82538, 82538, 25038, 1987, 37, 1, 1, 46, 4270, 89023, 480380, 825380, 480380
Offset: 0

Views

Author

Roger L. Bagula, Feb 05 2009

Keywords

Comments

Row sums are: A054091;
{1, 2, 4, 10, 32, 130, 652, 3914, 27400, 219202, 1972820, ...}.
The sequence comes from a generalization of the recurrence for A008517.

Examples

			{1},
{1, 1},
{1, 2, 1},
{1, 4, 4, 1},
{1, 7, 16, 7, 1},
{1, 11, 53, 53, 11, 1},
{1, 16, 150, 318, 150, 16, 1},
{1, 22, 380, 1554, 1554, 380, 22, 1},
{1, 29, 892, 6562, 12432, 6562, 892, 29, 1},
{1, 37, 1987, 25038, 82538, 82538, 25038, 1987, 37, 1},
{1, 46, 4270, 89023, 480380, 825380, 480380, 89023, 4270, 46, 1}
		

Crossrefs

Programs

  • Mathematica
    m = 1; e[n_, 0, m_] := 1;
    e[n_, k_, m_] := 0 /; k >= n;
    e[n_, k_, 1] := 1 /; k >= n;
    e[n_, k_, m_] := (k + m - 1)e[n - 1, k, m] + (m*n - k + 1 - m)e[n - 1, k - 1, m];
    Table[Table[e[n, k, m], {k, 0, n}], {n, 0, 10}];
    Flatten[%]

Formula

t(n,k) = (k + m - 1)*t(n - 1, k, m) + (m*n - k + 1 - m)*t(n - 1, k - 1, m).

A156186 Triangle: m=3; e(n,k,n) = (k + m - 1)*e(n - 1, k, m) + (m*n - k + 1 - m)*e(n - 1, k - 1, m); t(n,k) = e(n,k,m) + e(n,n-k,m).

Original entry on oeis.org

2, 1, 1, 1, 6, 1, 1, 30, 30, 1, 1, 159, 360, 159, 1, 1, 1119, 3639, 3639, 1119, 1, 1, 10932, 41262, 57414, 41262, 10932, 1, 1, 136764, 582642, 898632, 898632, 582642, 136764, 1, 1, 2031933, 9957168, 16634718, 17182152, 16634718, 9957168, 2031933, 1, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 05 2009

Keywords

Examples

			{2},
{1, 1},
{1, 6, 1},
{1, 30, 30, 1},
{1, 159, 360, 159, 1},
{1, 1119, 3639, 3639, 1119, 1},
{1, 10932, 41262, 57414, 41262, 10932, 1},
{1, 136764, 582642, 898632, 898632, 582642, 136764, 1},
{1, 2031933, 9957168, 16634718, 17182152, 16634718, 9957168, 2031933, 1},...
		

Crossrefs

Programs

  • Mathematica
    m = 3; e[n_, 0, m_] := 1;
    e[n_, k_, m_] := 0 /; k >= n;
    e[n_, k_, 1] := 1 /; k >= n;
    e[n_, k_, m_] := (k + m - 1)e[n - 1, k, m] + (m*n - k + 1 - m)e[n - 1, k - 1, m];
    Table[Table[e[n, k, m], {k, 0, n - 1}], {n, 1, 10}];
    Table[Table[e[n, k, m] + e[n, n - k, m], {k, 0, n}], {n, 0, 10}];
    Flatten[%]

Formula

m=3; e(n,k,n) = (k + m - 1)*e(n - 1, k, m) + (m*n - k + 1 - m)*e(n - 1, k - 1, m);
t(n,k) = e(n,k,m) + e(n,n-k,m).

A156188 Triangle: m=5; e(n,k,n)=(k + m - 1)*e(n - 1, k, m) + (m*n - k + 1 - m)*e(n - 1, k - 1, m); t(n,k)=e(n,k,m)+e(n,n-k,m).

Original entry on oeis.org

2, 1, 1, 1, 10, 1, 1, 80, 80, 1, 1, 775, 1520, 775, 1, 1, 10915, 25945, 25945, 10915, 1, 1, 213720, 542910, 624670, 542910, 213720, 1, 1, 5245530, 14690640, 16408670, 16408670, 14690640, 5245530, 1, 1, 151534685, 479956020, 553630850, 464654480
Offset: 0

Views

Author

Roger L. Bagula, Feb 05 2009

Keywords

Examples

			{2},
{1, 1},
{1, 10, 1},
{1, 80, 80, 1},
{1, 775, 1520, 775, 1},
{1, 10915, 25945, 25945, 10915, 1},
{1, 213720, 542910, 624670, 542910, 213720, 1},
{1, 5245530, 14690640, 16408670, 16408670, 14690640, 5245530, 1},...
		

Crossrefs

Programs

  • Mathematica
    m = 5; e[n_, 0, m_] := 1;
    e[n_, k_, m_] := 0 /; k >= n;
    e[n_, k_, 1] := 1 /; k >= n;
    e[n_, k_, m_] := (k + m - 1)e[n - 1, k, m] + (m*n - k + 1 - m)e[n - 1, k - 1, m];
    Table[Table[e[n, k, m], {k, 0, n - 1}], {n, 1, 10}];
    Table[Table[e[n, k, m] + e[n, n - k, m], {k, 0, n}], {n, 0, 10}];
    Flatten[%]

Formula

m=5; e(n,k,n) = (k + m - 1)*e(n - 1, k, m) + (m*n - k + 1 - m)*e(n - 1, k - 1, m);
t(n,k) = e(n,k,m) + e(n,n-k,m).

A156278 A higher order recursion triangle sequence: m=3;l=3;e(n,k,m)=(l*k + m - 1)e(n - 1, k, m) + (m*n - l*k + 1 - m)e(n - 1, k - 1, m).

Original entry on oeis.org

1, 1, 1, 1, 9, 1, 1, 52, 44, 1, 1, 270, 716, 187, 1, 1, 1363, 8428, 7069, 762, 1, 1, 6831, 85143, 162039, 60151, 3065, 1, 1, 34174, 790440, 2889288, 2462504, 473162, 12280, 1, 1, 170892, 6972826, 44429208, 72035800, 32668794, 3557734, 49143, 1, 1, 854485
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Feb 07 2009

Keywords

Comments

Row sums are:
{2, 2, 4, 22, 196, 2350, 35248, 634462, 13323700, 319768798, 8633757544,...}.
The MacMahon level generalization that I was looking for:
I can get the Sierpinski Pascal mostly by this method too.
I did it by looking at the three variables {n,k,m} as being a 3d plane and the General -Sierpinski-Pascal like
{{m,0,0},
{0,-m,0},
{0,0,1}}. {n,k,1}
and the General Eulerian as being like:
{{m,0,0},
{0,-1,1},
{0,0-m}}. {n,k,1}
So the MacMahon is the next quantum step up in k:
{{m,0,0},
{0,-2,1},
{0,0-m}}. {n,k,1}
The further generalization adds a new quantum variable l:
{{m,0,0},
{0,-l,1},
{0,0-m}}. {n,k,1}
This recursive result seems to give a much more general type of combinatorial triangle sequence.

Examples

			{1},
{1, 1},
{1, 9, 1},
{1, 52, 44, 1},
{1, 270, 716, 187, 1},
{1, 1363, 8428, 7069, 762, 1},
{1, 6831, 85143, 162039, 60151, 3065, 1},
{1, 34174, 790440, 2889288, 2462504, 473162, 12280, 1},
{1, 170892, 6972826, 44429208, 72035800, 32668794, 3557734, 49143, 1},
{1, 854485, 59542232, 621204982, 1719368528, 1491834898, 397842620, 26034427, 196598, 1}
		

Crossrefs

Programs

  • Mathematica
    m = 3; l = 3;
    e[n_, 0, m_] := 1; e[n_, k_, m_] := 0 /; k >= n;
    e[n_, k_, 1] := 1 /; k >= n
    e[n_, k_, m_] := (l*k + m - 1)e[ n - 1, k, m] + (m*n - l*k + 1 - m)e[n - 1, k - 1, m];
    Table[Table[e[n, k, m], {k, 0, n - 1}], {n, 1, 10}];
    Flatten[%]

Formula

m=3;l=3;
e(n,k,m)=(l*k + m - 1)e(n - 1, k, m) + (m*n - l*k + 1 - m)e(n - 1, k - 1, m).

A156280 A higher order recursion triangle sequence: m=4;l=4;e(n,k,m)=(l*k + m - 1)e(n - 1, k, m) + (m*n - l*k + 1 - m)e(n - 1, k - 1, m).

Original entry on oeis.org

1, 1, 1, 1, 12, 1, 1, 93, 71, 1, 1, 664, 1618, 370, 1, 1, 4665, 26430, 20112, 1869, 1, 1, 32676, 370035, 645270, 216519, 9368, 1, 1, 228757, 4756581, 15969645, 12502371, 2164135, 46867, 1, 1, 1601328, 58041316, 339432876, 509029014, 212305928
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Feb 07 2009

Keywords

Comments

Row sums are:
{1, 1, 2, 14, 166, 2654, 53078, 1273870, 35668358, 1141387454, 41089948342,...}.
The MacMahon level generalization that I was looking for:
I can get the Sierpinski Pascal mostly by this method too.
I did it by looking at the three variables {n,k,m} as being a 3d plane and the General -Sierpinski-Pascal like
{{m,0,0},
{0,-m,0},
{0,0,1}}. {n,k,1}
and the General Eulerian as being like:
{{m,0,0},
{0,-1,1},
{0,0-m}}. {n,k,1}
So the MacMahon is the next quantum step up in k:
{{m,0,0},
{0,-2,1},
{0,0-m}}. {n,k,1}
The further generalization adds a new quantum variable l:
{{m,0,0},
{0,-l,1},
{0,0-m}}. {n,k,1}
This recursive result seems to give a much more general type of combinatorial triangle sequence.

Examples

			{1},
{1, 1},
{1, 12, 1},
{1, 93, 71, 1},
{1, 664, 1618, 370, 1},
{1, 4665, 26430, 20112, 1869, 1},
{1, 32676, 370035, 645270, 216519, 9368, 1},
{1, 228757, 4756581, 15969645, 12502371, 2164135, 46867, 1},
{1, 1601328, 58041316, 339432876, 509029014, 212305928, 20742624, 234366, 1},
{1, 11209329, 684892988, 6542526040, 16799641662, 13536529582, 3320027912, 193948962, 1171865, 1}
		

Crossrefs

Programs

  • Mathematica
    m = 4; l = 4;
    e[n_, 0, m_] := 1; e[n_, k_, m_] := 0 /; k >= n;
    e[n_, k_, 1] := 1 /; k >= n
    e[n_, k_, m_] := (l*k + m - 1)e[ n - 1, k, m] + (m*n - l*k + 1 - m)e[n - 1, k - 1, m];
    Table[Table[e[n, k, m], {k, 0, n - 1}], {n, 1, 10}];
    Flatten[%]

Formula

m=4;l=4;
e(n,k,m)=(l*k + m - 1)e(n - 1, k, m) + (m*n - l*k + 1 - m)e(n - 1, k - 1, m).

A219512 Triangle of third-order Eulerian numbers: 3-Stirling permutations enumerated by ascents.

Original entry on oeis.org

1, 1, 3, 1, 12, 15, 1, 33, 141, 105, 1, 78, 786, 1830, 945, 1, 171, 3450, 17538, 26685, 10395, 1, 360, 13257, 125352, 396495, 435960, 135135, 1, 741, 46971, 753291, 4238811, 9356175, 7921305, 2027025, 1, 1506, 157956, 4046526, 37013166, 140913270, 233216460, 158799690, 34459425
Offset: 1

Views

Author

Peter Bala, Dec 11 2012

Keywords

Comments

See A008292 for the triangle of Eulerian numbers and A008517 for the triangle of second-order Eulerian numbers (2-Stirling permutations).
A 3-Stirling permutation of order n is a permutation of the multiset {1,1,1,2,2,2,...,n,n,n} such that for each i, 1 <= i <= n, the elements occurring between two occurrences of i are at least i. This triangle enumerates 3-Stirling permutations by ascents. Examples are given below.

Examples

			Triangle begins
.n\k.|..0....1......2.......3......4........5.......6
= = = = = = = = = = = = = = = = = = = = = = = = = = =
..1..|..1
..2..|..1....3
..3..|..1...12.....15
..4..|..1...33....141.....105
..5..|..1...78....786....1830....945
..6..|..1..171...3450...17538..26685....10395
..7..|..1..360..13257..125352.396495...435960..135135
...
Example of recurrence: T(5,2) = 3*141 + 11*33 = 786.
Row 2 = [1,3]. The 3-Stirling permutations of order 2 are obtained by inserting the string 222 into one of the four available positions in the string 111, giving 222111, 122211, 112221 and 111222. The first permutation has no ascents while the remaining three permutations each have 1 ascent.
		

Crossrefs

Cf. A001147 (main diagonal), A007559 (row sums), A008292, A008517.

Programs

  • Mathematica
    T[n_, k_] /; 1 <= k <= n-1 := T[n, k] = (k+1) T[n-1, k] + (3n-k-2) T[n-1, k-1]; T[, 0] = 1; T[, _] = 0;
    Table[T[n, k], {n, 1, 9}, {k, 0, n-1}] // Flatten (* Jean-François Alcover, Nov 12 2019 *)

Formula

Recurrence equation: T(n+1,k) = (k + 1)*T(n,k) + (3*n - k + 1)*T(n,k-1).
Let B(x,t) = Integral_{x' = 0..x} 1/((1 + x')*( 1+ t*x')^3) dx' = x - (1 + 3*t)*x^2/2 + (1 + 3*t + 6*t^2)*x^3/3 - (1 + 3*t + 6*t^2 + 10*t^3)*x^4/4 + ....
The e.g.f. A(x,t) appears to be the series reversion (with respect to x) B(x,t)^<-1> = x + (1 + 3*t)*x^2/2! + (1 + 12*t + 15*t^2)*x^3/3! + .... If true, then the e.g.f. A(x,t) satisfies the autonomous differential equation dA/dx = (1 + A)*(1 + t*A)^3, A(0,t) = 0. Also if we let D be the operator (1 + x)*(1 + t*x)^3*d/dx then the (n+1)-th row polynomial R(n+1,t) = D^n(x) evaluated at x = 0.

A321591 Partitioned 2nd-order Eulerian numbers forming an "Eulerian pyramid" (tetrahedron).

Original entry on oeis.org

1, 1, 1, 1, 1, 4, 4, 1, 4, 1, 1, 11, 11, 11, 36, 11, 1, 11, 11, 1, 1, 26, 26, 66, 196, 66, 26, 196, 196, 26, 1, 26, 66, 26, 1, 1, 57, 57, 302, 848, 302, 302, 1898, 1898, 302, 57, 848, 1898, 848, 57, 1, 57, 302, 302, 57, 1, 1, 120, 120, 1191, 3228, 1191, 2416, 13644
Offset: 0

Views

Author

Gregory Gerard Wojnar, Nov 13 2018

Keywords

Comments

For N+1 = i+j+k, let P(N+1;i,j,k) = (N+1-i)*P(N;i-1,j,k) + (N+1-j)*P(N;i,j-1,k) + (N+1-k)*P(N;i,j,k-1), with P(N;i,j,k) invariant upon permutation of the indices i,j,k, also P(N;N,0,0)=1 and P(N;i,j,k) = 0 if i or j or k is negative. The indexing of these values is shown explicitly in the examples.
The row sums are the second-order Eulerian numbers, A008517; precisely, Sum_{(j,k)|j+k=N-i} P(N;i,j,k) = <> = T(N+1,i+1) of A008517. The row sum of row i=N of slice N is (N+1)!. The sum of all entries in slice N is (2*N+1)!!. The edges of the N-th triangular slice of the pyramid are row (N+1) of the first-order Eulerian triangle, A008292.

Examples

			The first few slices of the tetrahedron (and row sums) are:
  1                  (1); i=0, N=0, (j,k)=(0,0)
------------------------
   1                 (1); i=0, N=1, (j,k)=(0,0)
  1 1                (2); i=1, N=1, (j,k)=(1,0) (0,1)
------------------------
    1                (1); i=0, N=2, (j,k)=(0,0)
   4 4               (8); i=1, N=2, (j,k)=(1,0) (0,1)
  1 4 1              (6); i=2, N=2, (j,k)=(2,0) (1,1) (0,2)
------------------------
      1              (1); i=0, N=3, (j,k)=(0,0)
    11 11           (22); i=1, N=3, (j,k)=(1,0) (0,1)
   11 36 11         (58); i=2, N=3, (j,k)=(2,0) (1,1) (0,2)
  1 11 11  1        (24); i=3, N=3, (j,k)=(3,0) (2,1) (1,2) (0,3)
------------------------
         1           (1); i=0, N=4, (j,k)=(0,0)
       26 26        (52); i=1, N=4, (j,k)=(1,0) (0,1)
     66 196 66     (328); i=2, N=4, (j,k)=(2,0) (1,1) (0,2)
   26 196 196 26   (444); i=3, N=4, (j,k)=(3,0) (2,1) (1,2) (0,3)
  1  26  66  26 1  (120); i=4, N=4, (j,k)=(4,0) (3,1) (2,2) (1,3) (0,4)
		
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