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 1-4 of 4 results.

A061697 Generalized Bell numbers.

Original entry on oeis.org

1, 0, 0, 1, 1, 1, 201, 1226, 5587, 493333, 8910253, 109739620, 6832444928, 251336859489, 6402632091649, 369288128260091, 21333939590516867, 941843896620169405, 60266201588496408645, 4623833509894543300868, 309412778502377193367456, 24102475277979402591991181
Offset: 0

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Author

N. J. A. Sloane, Jun 19 2001

Keywords

Crossrefs

Formula

Sum_{n>=0} a(n) * x^n / (n!)^2 = exp(BesselI(0,2*sqrt(x)) - 1 - x - x^2/4). - Ilya Gutkovskiy, Jul 12 2020

Extensions

More terms from Ilya Gutkovskiy, Jul 12 2020

A337166 Sum_{n>=0} a(n) * x^n / (n!)^2 = exp(1 + x - BesselI(0,2*sqrt(x))).

Original entry on oeis.org

1, 0, -1, -1, 17, 99, -926, -20385, 25969, 7206059, 90298826, -3271747557, -149187119280, 236884125841, 233237751740057, 7110791842650002, -293292401726383791, -32980038867059802549, -498084376275585698222, 114298048468067933019627, 9072219653673352772098960
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 28 2021

Keywords

Crossrefs

Programs

  • Maple
    A337166 := proc(n)
        option remember ;
        if n = 0 then
            1;
        else
            add(binomial(n,k)^2*(n-k)*procname(k),k=0..n-2) ;
            -%/n ;
        end if;
        simplify(%) ;
    end proc:
    seq(A337166(n),n=0..40) ; # R. J. Mathar, Aug 19 2022
  • Mathematica
    nmax = 20; CoefficientList[Series[Exp[1 + x - BesselI[0, 2 Sqrt[x]]], {x, 0, nmax}], x] Range[0, nmax]!^2
    a[0] = 1; a[n_] := a[n] = -(1/n) Sum[Binomial[n, k]^2 (n - k) a[k], {k, 0, n - 2}]; Table[a[n], {n, 0, 20}]

Formula

a(0) = 1; a(n) = -(1/n) * Sum_{k=0..n-2} binomial(n,k)^2 * (n-k) * a(k).

A346271 Sum_{n>=0} a(n) * x^n / (n!)^2 = exp( BesselI(0,2*sqrt(x)) - 1 - x^2 / 4 ).

Original entry on oeis.org

1, 1, 2, 7, 41, 346, 3807, 53747, 952275, 20362552, 515112983, 15277888693, 523304644304, 20415373547609, 900219731675981, 44533809102813206, 2451041479421900803, 149140880201760643360, 9982798939295116151967, 731215136812226462200109, 58333374310397488522052976
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 12 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Exp[BesselI[0, 2 Sqrt[x]] - 1 - x^2/4], {x, 0, nmax}], x] Range[0, nmax]!^2
    a[0] = 1; a[n_] := a[n] = n a[n - 1] + (1/n) Sum[Binomial[n, k]^2 k a[n - k], {k, 3, n}]; Table[a[n], {n, 0, 20}]

Formula

Sum_{n>=0} a(n) * x^n / (n!)^2 = exp( x + Sum_{n>=3} x^n / (n!)^2 ).
a(0) = 1; a(n) = n * a(n-1) + (1/n) * Sum_{k=3..n} binomial(n,k)^2 * k * a(n-k).

A346272 Sum_{n>=0} a(n) * x^n / (n!)^2 = exp( BesselI(0,2*sqrt(x)) - 1 - x^3 / 36 ).

Original entry on oeis.org

1, 1, 3, 15, 115, 1196, 16282, 276158, 5713507, 140482000, 4047179258, 134447125418, 5097852537802, 218254682152053, 10469861372693621, 558373926672949031, 32908746221003292003, 2130712239317226923136, 150826951188229240683858, 11618459541824256750732794
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 12 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 19; CoefficientList[Series[Exp[BesselI[0, 2 Sqrt[x]] - 1 - x^3/36], {x, 0, nmax}], x] Range[0, nmax]!^2
    a[0] = a[1] = 1; a[n_] := a[n] = n a[n - 1] + n (n - 1)^2 a[n - 2]/2 + (1/n) Sum[Binomial[n, k]^2 k a[n - k], {k, 4, n}]; Table[a[n], {n, 0, 19}]

Formula

Sum_{n>=0} a(n) * x^n / (n!)^2 = exp( x + x^2 / 4 + Sum_{n>=4} x^n / (n!)^2 ).
a(0) = a(1) = 1; a(n) = n * a(n-1) + n * (n-1)^2 * a(n-2) / 2 + (1/n) * Sum_{k=4..n} binomial(n,k)^2 * k * a(n-k).
Showing 1-4 of 4 results.