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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A295182 a(n) = n! * [x^n] exp(-n*x)/(1 - x)^n.

Original entry on oeis.org

1, 0, 2, 6, 72, 620, 8640, 122346, 2156672, 41367672, 905126400, 21646532270, 570077595648, 16268377195044, 502096929431552, 16629319748711250, 588938142209310720, 22196966267762213744, 887352465220427317248, 37496112562144553167062, 1670071417348195942400000, 78195398849926292810318940
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 16 2017

Keywords

Comments

The n-th term of the n-fold exponential convolution of A000166 with themselves.

Crossrefs

Programs

  • Maple
    S:= series((exp(-x)/(1-x))^n,x,30):
    seq(n!*coeff(S,x,n),n=0..29); # Robert Israel, Nov 16 2017
  • Mathematica
    Table[n! SeriesCoefficient[Exp[-n x]/(1 - x)^n, {x, 0, n}], {n, 0, 21}]

Formula

a(n) = A295181(n,n).
a(n) ~ phi^(3*n - 1/2) * n^n / (5^(1/4) * exp(n*(1 + 1/phi))), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Nov 16 2017
a(n) = n! * Sum_{k=0..n} (-n)^(n-k) * binomial(n+k-1,k)/(n-k)!. - Seiichi Manyama, Apr 25 2025

A383344 Expansion of e.g.f. exp(-4*x) / (1-x)^4.

Original entry on oeis.org

1, 0, 4, 8, 72, 416, 3520, 31104, 316288, 3525632, 43117056, 572195840, 8191304704, 125761056768, 2060841582592, 35894401335296, 662066514984960, 12890305925218304, 264155723747688448, 5682905054074109952, 128051031032232411136, 3015653024970577018880
Offset: 0

Views

Author

Seiichi Manyama, Apr 23 2025

Keywords

Crossrefs

Column k=4 of A295181.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-4*x)/(1-x)^4))

Formula

a(n) = n! * Sum_{k=0..n} (-4)^(n-k) * binomial(k+3,3)/(n-k)!.
a(n) = (n-1) * (a(n-1) + 4*a(n-2)) for n > 1.
E.g.f.: B(x)^4, where B(x) is the e.g.f. of A000166.
a(n) ~ sqrt(2*Pi) * n^(n + 7/2) / (6*exp(n+4)). - Vaclav Kotesovec, Apr 25 2025

A383381 Expansion of e.g.f. exp(-2*x) / (1-x)^5.

Original entry on oeis.org

1, 3, 14, 82, 576, 4688, 43264, 445632, 5062016, 62812288, 844863744, 12239474432, 189939644416, 3142842052608, 55223903596544, 1026805938614272, 20139224002953216, 415503046091767808, 8994794537935765504, 203848794955954716672, 4826475681472562855936, 119162892472107134353408
Offset: 0

Views

Author

Seiichi Manyama, Apr 24 2025

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-2*x)/(1-x)^5))

Formula

a(n) = n! * Sum_{k=0..n} (-2)^(n-k) * binomial(k+4,4)/(n-k)!.
a(0) = 1, a(1) = 3; a(n) = (n+2)*a(n-1) + 2*(n-1)*a(n-2).
a(n) ~ sqrt(2*Pi) * n^(n + 9/2) / (24*exp(n+2)). - Vaclav Kotesovec, Apr 25 2025

A087982 Maximal permanent of a nonsingular n X n (+1,-1)-matrix.

Original entry on oeis.org

1, 0, 2, 8, 24, 128
Offset: 1

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Author

N. J. A. Sloane, Oct 28 2003

Keywords

Comments

It is conjectured by Kraeuter and Seifter that for n >= 5 the maximal permanent of a nonsingular n X n (+1,-1)-matrix is attained by a matrix with exactly n-1 -1's on the diagonal (compare A087981).
This has been proved by Budrevich and Guterman. - Sergei Shteiner, Jan 21 2020
The maximal possible value for the permanent of a singular n X n (+1,-1)-matrix is obviously n!.

Examples

			a(4) = 8 from the following matrix:
-1 +1 +1 +1
+1 +1 +1 +1
+1 -1 +1 -1
-1 +1 +1 -1
		

Crossrefs

For n != 4 this is given by A087981. Cf. A087983.

Formula

a(n) = A087981(n-1) for n >= 5. - Sergei Shteiner, Jan 20 2020

Extensions

a(4) = 8 from W. Edwin Clark and Wouter Meeussen, a(5) = 24 and a(6) = 128 from Jaap Spies, Oct 29 2003

A335111 a(n) = n! * Sum_{k=0..n-1} (-2)^k / k!.

Original entry on oeis.org

0, 1, -2, 6, -8, 40, 48, 784, 5248, 49536, 490240, 5403904, 64822272, 842742784, 11798284288, 176974510080, 2831591636992, 48137058942976, 866467058614272, 16462874118651904, 329257482362552320, 6914407129635618816, 152116956851937476608, 3498690007594658430976
Offset: 0

Views

Author

Ilya Gutkovskiy, May 23 2020

Keywords

Comments

Inverse binomial transform of A000240.

Crossrefs

Programs

  • Mathematica
    Table[n! Sum[(-2)^k/k!, {k, 0, n - 1}], {n, 0, 23}]
    nmax = 23; CoefficientList[Series[Sum[k! x^k/(1 + 2 x)^(k + 1), {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 23; CoefficientList[Series[x Exp[-2 x]/(1 - x), {x, 0, nmax}], x] Range[0, nmax]!
  • PARI
    a(n) = n! * sum(k=0, n-1, (-2)^k / k!); \\ Michel Marcus, May 23 2020

Formula

G.f.: Sum_{k>=1} k! * x^k / (1 + 2*x)^(k + 1).
E.g.f.: x*exp(-2*x) / (1 - x).
a(n) = A000023(n) - A122803(n).
a(n) ~ exp(-2) * n!. - Vaclav Kotesovec, Jun 08 2022
a(n) = Sum_{k=0..n} (-1)^k * k * A008290(n,k). - Alois P. Heinz, May 20 2023

A383380 Expansion of e.g.f. exp(-2*x) / (1-x)^4.

Original entry on oeis.org

1, 2, 8, 40, 248, 1808, 15136, 142784, 1496960, 17254144, 216740864, 2945973248, 43065951232, 673626675200, 11224114860032, 198447384666112, 3710328985124864, 73136238041563136, 1515739708283944960, 32947698735175172096, 749499782353468522496, 17806903161183314378752
Offset: 0

Views

Author

Seiichi Manyama, Apr 24 2025

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-2*x)/(1-x)^4))

Formula

E.g.f.: B(x)^2, where B(x) is the e.g.f. of A000255.
a(n) = n! * Sum_{k=0..n} (-2)^(n-k) * binomial(k+3,3)/(n-k)!.
a(0) = 1, a(1) = 2; a(n) = (n+1)*a(n-1) + 2*(n-1)*a(n-2).
a(n) ~ sqrt(Pi) * n^(n + 7/2) / (3*sqrt(2)*exp(n+2)). - Vaclav Kotesovec, Apr 25 2025

A176097 Degree of the hyperdeterminant of the cubic format (k+1) X (k+1) X (k+1).

Original entry on oeis.org

1, 4, 36, 272, 2150, 16992, 134848, 1072192, 8536914, 68036600, 542607560, 4329671040, 34561892560, 275979195520, 2204266118400, 17609217372416, 140698273234634, 1124340854572296, 8985828520591912, 71822662173752800
Offset: 0

Views

Author

Benjamin J. Young, Apr 08 2010

Keywords

Examples

			For k=1, the hyperdeterminant of the matrix (a_ijk) (for 0 <= i,j,k <= 1) is (a_000 * a_111)^2 + (a001 * a110)^2 + (a_010 * a_101)^2 + (a_011 * a_100)^2 -2(a_000 * a_001 * a_110 * a_111 + a_000 * a_010 * a_101 * a_111 + a_000 * a_011 * a_100 * a_111 + a_001 * a_010 * a_101 * a_110 + a_001 * a_011 * a_110 * a_100 + a_010 * a_011 * a_101 * a_100) + 4(a_000 * a_011 * a_101 * a_110 + a_001 * a_010 * a_100 * a_111) (see Gelfand, Kapranov & Zelevinsky, pp. 2 and 448.) [Corrected by _Petros Hadjicostas_, Sep 12 2019]
		

References

  • I. M. Gelfand, M. M. Kapranov and A. V. Zelevinsky, Discriminants, Resultants and Multidimensional Determinants, Birkhauser, 2008, p. 456 (Ch. 14, Corollary 2.9).

Crossrefs

Programs

  • Maple
    a:= k-> add((j+k+1)! /(j!)^3 /(k-2*j)! *2^(k-2*j), j=0..floor(k/2)): seq(a(n), n=0..20);
    # Second program:
    a := proc(n) option remember; if n = 0 then return 1 elif n = 1 then return 4 fi;
    (a(n-1)*(21*n^3-10*n^2-9*n+6)+a(n-2)*(24*n^3+16*n^2))/((3*n-1)*n^2) end:
    seq(a(n), n=0..19); # Peter Luschny, Sep 12 2019
  • Mathematica
    Table[Sum[(j + n + 1)!*2^(n - 2*j)/(j!^3*(n - 2*j)!), {j, 0, n/2}], {n, 0, 20}] (* Vaclav Kotesovec, Sep 12 2019 *)

Formula

a(n) = Sum_{j = 0..n/2} ( (j+n+1)! * 2^(n-2j) )/((j!)^3 * (n-2j)!).
a(n) = (n+1)^2*(8*A000172(n)-A000172(n+1))/6. - Mark van Hoeij, Jul 02 2010
G.f.: hypergeom([-1/3, 1/3],[1],27*x^2/(1-2*x)^3)*(1-2*x)/((x+1)^2*(1-8*x)). - Mark van Hoeij, Apr 11 2014
a(n) ~ 8^(n+1) / (Pi * 3^(3/2)). - Vaclav Kotesovec, Sep 12 2019
a(n) = (a(n-1)*(21*n^3 - 10*n^2 - 9*n + 6) + a(n-2)*(24*n^3 + 16*n^2))/((3*n - 1)*n^2) for n >= 2. - Peter Luschny, Sep 12 2019

A335595 E.g.f.: exp(-x * (2 + x)) / (1 - x)^2.

Original entry on oeis.org

1, 0, 0, 4, 12, 48, 400, 3120, 25872, 251776, 2715264, 31809600, 405296320, 5580385536, 82469607168, 1302102360832, 21875297337600, 389590168842240, 7331376554610688, 145352459953603584, 3028176414606560256, 66135374473635328000, 1510938930307368898560, 36038691473858577444864
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 20 2020

Keywords

Crossrefs

Programs

  • Maple
    A335595 := proc(n)
        option remember ;
        if n = 0 then
            1;
        else
            2*add(binomial(n-1,k-1)*(k-1)!*procname(n-k),k=3..n) ;
        end if;
    end proc:
    seq(A335595(n),n=0..42) ; # R. J. Mathar, Aug 20 2021
  • Mathematica
    nmax = 23; CoefficientList[Series[Exp[-x (2 + x)]/(1 - x)^2, {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = 2 Sum[Binomial[n - 1, k - 1] (k - 1)! a[n - k], {k, 3, n}]; Table[a[n], {n, 0, 23}]
    Table[Sum[Binomial[n, k] HermiteH[k, -1] (n - k + 1)!, {k, 0, n}], {n, 0, 23}]
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace(exp(-x*(2+x))/(1-x)^2)) \\ Michel Marcus, Nov 21 2020

Formula

a(0) = 1; a(n) = 2 * Sum_{k=3..n} binomial(n-1,k-1) * (k-1)! * a(n-k).
a(n) = Sum_{k=0..n} binomial(n,k) * Hermite(k,-1) * (n-k+1)!.
a(n) = Sum_{k=0..n} binomial(n,k) * A038205(k) * A038205(n-k).
a(n) ~ exp(-3) * n * n!. - Vaclav Kotesovec, Aug 09 2021
D-finite with recurrence a(n) +(-n+1)*a(n-1) -2*(n-1)*(n-2)*a(n-3)=0. - R. J. Mathar, Aug 20 2021

A176901 Number of 3 X n semireduced Latin rectangles, that is, having exactly n fixed points in the first two rows.

Original entry on oeis.org

4, 72, 1584, 70720, 3948480, 284570496, 25574768128, 2808243910656, 369925183388160, 57585548812887040, 10458478438093154304, 2191805683821733404672, 525011528578874444283904, 142540766765931981615759360, 43542026550306796238178877440, 14867182204795857282384287236096, 5640920219495105293649671985430528
Offset: 3

Views

Author

Vladimir Shevelev, Apr 28 2010

Keywords

Comments

A Latin rectangle is called reduced if its first row is [1,2,...,n] (the number of 3 X n reduced Latin rectangles is given in A000186). Therefore a Latin rectangle having exactly n fixed points in the first two rows may be called "semireduced". Thus if A1(i), A2(i), i=1,...,n, are the first two rows, then, for every i, either A1(i)=i or A2(i)=i.

Crossrefs

Formula

Let F_n = A087981(n) = n! * Sum_{2*k_2+...+n*k_n=n, k_i>=0} Product_{i=2..n} 2^k_i/(k_i!*i^k_i). Then a(n) = Sum_{k=0..floor(n/2)} binomial(n,k) * F_k * F_(n-k) * u_(n-2*k), where u(n) = A000179(n). - Vladimir Shevelev, Mar 30 2016

Extensions

More terms from William P. Orrick, Jul 25 2020

A337615 T(n, k) = binomial(n, k)*sf(n-k)*sf(k) where sf is the subfactorial (A000166). Triangle read by rows, for 0 <= k <= n.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 2, 0, 0, 2, 9, 0, 6, 0, 9, 44, 0, 20, 20, 0, 44, 265, 0, 135, 80, 135, 0, 265, 1854, 0, 924, 630, 630, 924, 0, 1854, 14833, 0, 7420, 4928, 5670, 4928, 7420, 0, 14833, 133496, 0, 66744, 44520, 49896, 49896, 44520, 66744, 0, 133496
Offset: 0

Views

Author

Peter Luschny, Sep 05 2020

Keywords

Examples

			Triangle starts:
[0]      1;
[1]      0, 0;
[2]      1, 0,     1;
[3]      2, 0,     0,     2;
[4]      9, 0,     6,     0,     9;
[5]     44, 0,    20,    20,     0,    44;
[6]    265, 0,   135,    80,   135,     0,   265;
[7]   1854, 0,   924,   630,   630,   924,     0,  1854;
[8]  14833, 0,  7420,  4928,  5670,  4928,  7420,     0, 14833;
[9] 133496, 0, 66744, 44520, 49896, 49896, 44520, 66744,     0, 133496.
		

Crossrefs

Cf. A000166 (T(n,0) and T(n,n)), A087981 (row sums).

Programs

  • Maple
    sf := n -> add((-1)^(n-j)*pochhammer(n-j+1, j), j=0..n):
    T := (n, k) -> binomial(n,k)*sf(n-k)*sf(k):
    seq(seq(T(n, k), k=0..n), n=0..9);
Previous Showing 11-20 of 21 results. Next