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 1-7 of 7 results.

A211212 4-alternating permutations of length 4n.

Original entry on oeis.org

1, 1, 69, 33661, 60376809, 288294050521, 3019098162602349, 60921822444067346581, 2159058013333667522020689, 125339574046311949415000577841, 11289082167259099068433198467575829, 1510335441937894173173702826484473600301
Offset: 0

Views

Author

Peter Luschny, Apr 04 2012

Keywords

Comments

a(n) = A181985(4,n).

Crossrefs

Programs

  • Maple
    A211212 := proc(n) local E, dim, i, k; dim := 4*(n-1);
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
       if i mod 4 = 0 then E[i, 0] := 0 ;
          for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
       else E[0, i] := 0;
          for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
       fi od;
    E[0, dim] end:
    seq(A211212(i), i = 1..12);
    A211212_list := proc(size) local E, S;
    E := 2*exp(x*z)/(cosh(z)+cos(z));
    S := z -> series(E, z, 4*(size+1));
    seq((-1)^n*(4*n)!*subs(x=0, coeff(S(z), z, 4*n)), n=0..size-1) end:
    A211212_list(12); # Peter Luschny, Jun 06 2016
  • Mathematica
    A181985[n_, len_] := Module[{e, dim = n (len - 1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0, e[i, 0] = 0; For[k = i - 1, k >= 0, k--, e[k, i - k] = e[k + 1, i - k - 1] + e[k, i - k - 1]], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i - k] = e[k - 1, i - k + 1] + e[k - 1, i - k]]]]; Table[e[0, n k], {k, 0, len - 1}]];
    a[n_] := A181985[4, n + 1] // Last;
    Table[a[n], {n, 0, 11}] (* Jean-François Alcover, Jun 29 2019 *)
  • Sage
    # uses[A from A181936]
    A211212 = lambda n: A(4,4*n)*(-1)^n
    print([A211212(n) for n in (0..11)]) # Peter Luschny, Jan 24 2017

Formula

a(0) = 1; a(n) = Sum_{k=1..n} (-1)^(k+1) * binomial(4*n,4*k) * a(n-k). - Ilya Gutkovskiy, Jan 27 2020
E.g.f.: 1/(cos(x/sqrt(2))*cosh(x/sqrt(2))) = 1 + 1*z^4/4! + 69*z^8/8! + 33661*z^12/12! + ... - Michael Wallner, Nov 17 2020
a(n) ~ 2^(10*n + 9/2) * n^(4*n + 1/2) / (cosh(Pi/2) * Pi^(4*n + 1/2) * exp(4*n)). - Vaclav Kotesovec, Nov 17 2020

A181991 n-alternating permutations of length 4n.

Original entry on oeis.org

1, 1385, 315523, 60376809, 11593285251, 2301250545971, 472105349529479, 99537885358650089, 21451428576293883859, 4705284467293276073635, 1047067375984978044542143, 235809039854522043890582835, 53644722291938408687646120103, 12309355014854205055828909176039
Offset: 1

Views

Author

Peter Luschny, Apr 05 2012

Keywords

Comments

a(n) = A181985(n,4).

Crossrefs

Programs

  • Maple
    A181991 := proc(n) local E, dim, i, k; dim := 4*n;
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
    if i mod n = 0 then E[i, 0] := 0 ;
       for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
    else E[0, i] := 0;
       for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
    fi od; E[0, dim] end:
    seq(A181991(n), n = 1..14);
    # Alternatively:
    a := (x) -> (4*x)!*(-1/(4*x)!+2/x!/(3*x)!+1/(2*x)!^2-3/x!^2/(2*x)!+1/x!^4):
    seq(a(n), n=1..14); # Peter Luschny, Aug 13 2015
  • Mathematica
    A181985[n_, len_] := Module[{e, dim = n*(len - 1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0, e[i, 0] = 0; For[k = i - 1, k >= 0, k--, e[k, i - k] = e[k + 1, i - k - 1] + e[k, i - k - 1]], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i - k] = e[k - 1, i - k + 1] + e[k - 1, i - k]]]]; Table[e[0, n*k], {k, 0, len - 1}]]; a[n_] := A181985[n, 4 + 1][[4 + 1]]; Table[a[n], {n, 1, 14}] (* Jean-François Alcover, Dec 17 2013, after Maple code in A181985 *)

Formula

a(n) = (4*n)!*(-1/(4*n)! + 2/(n!*(3*n)!) + 1/(2*n)!^2 - 3/(n!^2*(2*n)!) + 1/n!^4). - Peter Luschny, Aug 13 2015

A211213 n-alternating permutations of length 3n.

Original entry on oeis.org

1, 61, 1513, 33661, 750751, 17116009, 398840401, 9464040829, 227864057851, 5550936701311, 136526608389601, 3384729259165801, 84478081828015513, 2120572560190269841, 53494979095639780513, 1355345459896317255037, 34469858667289041256051, 879619727291950363099291
Offset: 1

Views

Author

Peter Luschny, Apr 05 2012

Keywords

Comments

a(n) = A181985(n,3).

Crossrefs

Programs

  • Maple
    A211213 := proc(n) local E, dim, i, k; dim := 3*n;
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
    if i mod n = 0 then E[i, 0] := 0 ;
       for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
    else E[0, i] := 0;
       for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
    fi od; E[0, dim] end:
    seq(A211213(n), n = 1..18);
    # Alternatively:
    a := x -> (3*x)!*(1/(3*x)!-2/(x!*(2*x)!)+1/(x!)^3):
    seq(a(n),n=1..18); # Peter Luschny, Aug 13 2015
  • Mathematica
    nmax = 18; a[n_] := Module[{e, dim = n*(nmax-1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0 , e[i, 0] = 0; For[k = i-1, k >= 0, k--, e[k, i-k] = e[k+1, i-k-1] + e[k, i-k-1] ], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i-k] = e[k-1, i-k+1] + e[k-1, i-k] ] ]]; e[0, 3*n]] ; Table[a[n], {n, 1, nmax}] (* Jean-François Alcover, Jul 26 2013, after Maple *)

Formula

a(n) = (3*n)!*(1/(3*n)!-2/(n!*(2*n)!)+1/(n!)^3). - Peter Luschny, Aug 13 2015

A292604 Triangle read by rows, coefficients of generalized Eulerian polynomials F_{2}(x).

Original entry on oeis.org

1, 1, 0, 5, 1, 0, 61, 28, 1, 0, 1385, 1011, 123, 1, 0, 50521, 50666, 11706, 506, 1, 0, 2702765, 3448901, 1212146, 118546, 2041, 1, 0, 199360981, 308869464, 147485535, 24226000, 1130235, 8184, 1, 0
Offset: 0

Views

Author

Peter Luschny, Sep 20 2017

Keywords

Comments

The generalized Eulerian polynomials F_{m}(x) are defined F_{m; 0}(x) = 1 for all m >= 0 and for n > 0:
F_{0; n}(x) = Sum_{k=0..n} A097805(n, k)*(x-1)^(n-k) with coeffs. in A129186.
F_{1; n}(x) = Sum_{k=0..n} A131689(n, k)*(x-1)^(n-k) with coeffs. in A173018.
F_{2; n}(x) = Sum_{k=0..n} A241171(n, k)*(x-1)^(n-k) with coeffs. in A292604.
F_{3; n}(x) = Sum_{k=0..n} A278073(n, k)*(x-1)^(n-k) with coeffs. in A292605.
F_{4; n}(x) = Sum_{k=0..n} A278074(n, k)*(x-1)^(n-k) with coeffs. in A292606.
The case m = 1 are the Eulerian polynomials whose coefficients are the Eulerian numbers which are displayed in Euler's triangle A173018.
Evaluated at x in {-1, 1, 0} these families of polynomials give for the first few m:
F_{m} : F_{0} F_{1} F_{2} F_{3} F_{4}
x = 1: A000012 A000142 A000680 A014606 A014608 ... (m*n)!/m!^n
x = 0: -- A000012 A000364 A002115 A211212 ... m-alternating permutations of length m*n.
Note that the constant terms of the polynomials are the generalized Euler numbers as defined in A181985. In this sense generalized Euler numbers are also generalized Eulerian numbers.

Examples

			Triangle starts:
[n\k][    0        1        2       3     4  5  6]
--------------------------------------------------
[0][      1]
[1][      1,       0]
[2][      5,       1,       0]
[3][     61,      28,       1,      0]
[4][   1385,    1011,     123,      1,    0]
[5][  50521,   50666,   11706,    506,    1, 0]
[6][2702765, 3448901, 1212146, 118546, 2041, 1, 0]
		

References

  • G. Frobenius. Über die Bernoullischen Zahlen und die Eulerschen Polynome. Sitzungsber. Preuss. Akad. Wiss. Berlin, pages 200-208, 1910.

Crossrefs

F_{0} = A129186, F_{1} = A173018, F_{2} is this triangle, F_{3} = A292605, F_{4} = A292606.
First column: A000364. Row sums: A000680. Alternating row sums: A002105.

Programs

  • Maple
    Coeffs := f -> PolynomialTools:-CoefficientList(expand(f), x):
    A292604_row := proc(n) if n = 0 then return [1] fi;
    add(A241171(n, k)*(x-1)^(n-k), k=0..n); [op(Coeffs(%)), 0] end:
    for n from 0 to 6 do A292604_row(n) od;
  • Mathematica
    T[n_, k_] /; 1 <= k <= n := T[n, k] = k (2 k - 1) T[n - 1, k - 1] + k^2 T[n - 1, k]; T[, 1] = 1; T[, _] = 0;
    F[2, 0][] = 1; F[2, n][x_] := Sum[T[n, k] (x - 1)^(n - k), {k, 0, n}];
    row[n_] := If[n == 0, {1}, Append[CoefficientList[ F[2, n][x], x], 0]];
    Table[row[n], {n, 0, 7}] (* Jean-François Alcover, Jul 06 2019 *)
  • Sage
    def A292604_row(n):
        if n == 0: return [1]
        S = sum(A241171(n, k)*(x-1)^(n-k) for k in (0..n))
        return expand(S).list() + [0]
    for n in (0..6): print(A292604_row(n))

Formula

F_{2; n}(x) = Sum_{k=0..n} A241171(n, k)*(x-1)^(n-k) for n>0 and F_{2; 0}(x) = 1.

A292605 Triangle read by rows, coefficients of generalized Eulerian polynomials F_{3;n}(x).

Original entry on oeis.org

1, 1, 0, 19, 1, 0, 1513, 166, 1, 0, 315523, 52715, 1361, 1, 0, 136085041, 30543236, 1528806, 10916, 1, 0, 105261234643, 29664031413, 2257312622, 42421946, 87375, 1, 0, 132705221399353, 45011574747714, 4637635381695, 153778143100, 1156669095, 699042, 1, 0
Offset: 0

Views

Author

Peter Luschny, Sep 20 2017

Keywords

Comments

See the comments in A292604.

Examples

			Triangle starts:
[n\k][       0         1         2       3  4  5]
--------------------------------------------------
[0][         1]
[1][         1,        0]
[2][        19,        1,        0]
[3][      1513,      166,        1,     0]
[4][    315523,    52715,     1361,     1,  0]
[5][ 136085041, 30543236,  1528806, 10916,  1, 0]
		

Crossrefs

F_{0} = A129186, F_{1} = A173018, F_{2} = A292604, F_{3} is this triangle, F_{4} = A292606.
First column: A002115. Row sums: A014606. Alternating row sums: A292609.

Programs

  • Maple
    Coeffs := f -> PolynomialTools:-CoefficientList(expand(f),x):
    A292605_row := proc(n) if n = 0 then return [1] fi;
    add(A278073(n, k)*(x-1)^(n-k), k=0..n); [op(Coeffs(%)), 0] end:
    for n from 0 to 6 do A292605_row(n) od;
  • Sage
    # uses[A278073_row from A278073]
    def A292605_row(n):
        if n == 0: return [1]
        L = A278073_row(n)
        S = sum(L[k]*(x-1)^(n-k) for k in (0..n))
        return expand(S).list() + [0]
    for n in (0..5): print(A292605_row(n))

Formula

F_{3; n}(x) = Sum_{k=0..n} A278073(n, k)*(x-1)^(n-k) for n>0 and F_{3; 0}(x) = 1.

A292606 Triangle read by rows, coefficients of generalized Eulerian polynomials F_{4;n}(x).

Original entry on oeis.org

1, 1, 0, 69, 1, 0, 33661, 988, 1, 0, 60376809, 2669683, 16507, 1, 0, 288294050521, 17033188586, 212734266, 261626, 1, 0, 3019098162602349, 223257353561605, 4297382231090, 17634518610, 4196345, 1, 0
Offset: 0

Views

Author

Peter Luschny, Sep 26 2017

Keywords

Comments

See the comments in A292604.

Examples

			Triangle starts:
[n\k][          0            1          2       3   4   5]
--------------------------------------------------
[0] [           1]
[1] [           1,           0]
[2] [          69,           1,         0]
[3] [       33661,         988,         1,      0]
[4] [    60376809,     2669683,     16507,      1,  0]
[5] [288294050521, 17033188586, 212734266, 261626,  1,  0]
		

Crossrefs

F_{0} = A129186, F_{1} = A173018, F_{2} = A292604, F_{3} = A292605, F_{4} is this triangle.
First column: A211212. Row sums: A014608. Alternating row sums: A292607.
Cf. A181985.

Programs

  • Maple
    Coeffs := f -> PolynomialTools:-CoefficientList(expand(f), x):
    A292606_row := proc(n) if n = 0 then return [1] fi;
    add(A278074(n, k)*(x-1)^(n-k), k=0..n); [op(Coeffs(%)), 0] end:
    for n from 0 to 6 do A292606_row(n) od;
  • Sage
    # uses[A278074_row from A278074]
    def A292606_row(n):
        if n == 0: return [1]
        L = A278074_row(n)
        S = sum(L[k]*(x-1)^(n-k) for k in (0..n))
        return expand(S).list() + [0]
    for n in (0..5): print(A292606_row(n))

Formula

F_{4; n}(x) = Sum_{k=0..n} A278074(n, k)*(x-1)^(n-k) for n>0 and F_{4; 0}(x) = 1.

A181992 n-alternating permutations of length n^2.

Original entry on oeis.org

1, 1, 5, 1513, 60376809, 613498040952501, 2655748106132754540814283, 7350748555338515554166266981278924209, 18155845241010181420704703186769135339279915667193169, 53121946985233865823079732996510797894348260342024814486694637630897821
Offset: 0

Views

Author

Peter Luschny, Apr 05 2012

Keywords

Comments

These are the generalized Euler numbers A181985(n, n) and also the André numbers A181937(n, n^2).

Crossrefs

Programs

  • Maple
    A181992 := proc(n) local E, dim, i, k; dim := n*n;
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
    if i mod n = 0 then E[i, 0] := 0 ;
       for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
    else E[0, i] := 0;
       for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
    fi od;
    E[0, dim] end:
    seq(A181992(i),i=0..9);
  • Mathematica
    A181985[n_, len_] := Module[{e, dim = n*(len - 1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0, e[i, 0] = 0; For[k = i - 1, k >= 0, k--, e[k, i - k] = e[k + 1, i - k - 1] + e[k, i - k - 1]], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i - k] = e[k - 1, i - k + 1] + e[k - 1, i - k]]]]; Table[e[0, n*k], {k, 0, len - 1}]]; a[n_] := A181985[n, n + 1][[n + 1]]; Table[a[n], {n, 1, 14}] (* Jean-François Alcover, Dec 17 2013, after Maple code in A181985 *)

Extensions

a(0)=1 prepended by Alois P. Heinz, Aug 12 2019
Showing 1-7 of 7 results.