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.

Previous Showing 31-40 of 41 results. Next

A277470 E.g.f.: arcsinh(x)/(1+LambertW(-x)).

Original entry on oeis.org

0, 1, 2, 11, 104, 1249, 18264, 318163, 6425152, 147344769, 3781848480, 107408279483, 3343875651456, 113227469886881, 4142804357946240, 162871544915116035, 6847004160475236352, 306495323034774157569, 14554502490109085839872, 730777840212988501198059
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 16 2016

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[ArcSinh[x]/(1+LambertW[-x]), {x, 0, 25}], x] * Range[0, 25]!
    Flatten[{0, Table[Sin[Pi*n/2] * (n-2)!!^2 + Sum[Sin[Pi*k/2] * Binomial[n, k] * (k-2)!!^2 * (n-k)^(n-k), {k, 1, n-1}], {n, 1, 25}]}] (* Vaclav Kotesovec, Oct 28 2016 *)
  • PARI
    x='x+O('x^50); concat([0], Vec(serlaplace(asinh(x)/(1 + lambertw(-x)) ))) \\ G. C. Greubel, Nov 07 2017

Formula

a(n) ~ arcsinh(exp(-1)) * n^n.
a(n) ~ (-1 + log(1 + sqrt(1+exp(2)))) * n^n.

A277485 E.g.f.: -exp(2*x)*LambertW(-x).

Original entry on oeis.org

0, 1, 6, 33, 216, 1865, 21228, 303765, 5222864, 104540337, 2383558740, 60933722069, 1725392415288, 53590463856345, 1811281159509500, 66172416761172885, 2598298697830360992, 109116931783034360801, 4880122696811960470692, 231565260558289051906965
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 17 2016

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[-Exp[2*x]*LambertW[-x], {x, 0, 20}], x]*Range[0, 20]!
    Table[Sum[Binomial[n, m]*Sum[Binomial[m, k]*k^(k-1), {k, 1, m}], {m, 1, n}], {n, 0, 20}]
  • PARI
    x='x+O('x^50); concat([0], Vec(serlaplace(- exp(2*x)*lambertw(-x) ))) \\ G. C. Greubel, Nov 08 2017

Formula

a(n) = Sum_{m=1..n} (binomial(n,m) * Sum_{k=1..m} binomial(m,k)*k^(k-1)).
a(n) ~ exp(2*exp(-1)) * n^(n-1).

A290824 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. exp(k*x)/(1 + LambertW(-x)).

Original entry on oeis.org

1, 1, 1, 1, 2, 4, 1, 3, 7, 27, 1, 4, 12, 43, 256, 1, 5, 19, 71, 393, 3125, 1, 6, 28, 117, 616, 4721, 46656, 1, 7, 39, 187, 985, 7197, 69853, 823543, 1, 8, 52, 287, 1584, 11123, 105052, 1225757, 16777216, 1, 9, 67, 423, 2521, 17429, 159093, 1829291, 24866481, 387420489, 1, 10, 84, 601, 3928, 27525, 243256, 2740111, 36922928, 572410513, 10000000000
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 11 2017

Keywords

Comments

A(n,k) is the k-th binomial transform of A000312 evaluated at n.

Examples

			E.g.f. of column k: A_k(x) = 1 + (k + 1)*x/1! + (k^2 + 2*k + 4)*x^2/2! + (k^3 + 3*k^2 + 12*k + 27)*x^3/3! + (k^4 + 4*k^3 + 24*k^2 + 108*k + 256)*x^4/4! + ...
Square array begins:
     1,     1,     1,     1,     1,     1, ...
     1,     2,     3,     4,     5,     6, ...
     4,     7,    12,    19,    28,    39, ...
    27,    43,    71,   117,   187,   287, ...
   256,   393,   616,   985,  1584,  2521, ...
  3125,  4721,  7197, 11123, 17429, 27525, ...
		

Crossrefs

Columns k=0..2 give A000312, A086331, A277457.
Main diagonal gives A290840.

Programs

  • Mathematica
    Table[Function[k, n!*SeriesCoefficient[Exp[k x]/(1 + LambertW[-x]), {x, 0, n}]][j - n], {j, 0, 10}, {n, 0, j}] // Flatten (* G. C. Greubel, Nov 09 2017 *)

Formula

E.g.f. of column k: exp(k*x)/(1 + LambertW(-x)).
A(n,k) = Sum_{j=0..n} binomial(n,j)*k^(n-j)*j^j. - Fabian Pereyra, Jul 16 2024

A336213 a(n) = Sum_{k=0..n} k^k * binomial(n,k)^n, with a(0)=1.

Original entry on oeis.org

1, 2, 9, 163, 12609, 3906251, 4835455813, 23882051929709, 470073929716006913, 36867039626275056203923, 11562789460238169439667262501, 14393917436542502296957220221339601, 72060131612303615870363237649174605005057, 1424448870088911493303605765206905153730451241313
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 12 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Table[1 + Sum[k^k * Binomial[n, k]^n, {k, 1, n}], {n, 0, 15}]
  • PARI
    a(n) = if (n==0, 1, sum(k=0, n, k^k * binomial(n,k)^n)); \\ Michel Marcus, Jul 13 2020

Formula

Let f(n) = exp(-1/4) * QPochhammer(exp(-4)) * 2^(n^2 - 1/4) * exp((3*log(n)^2 + 3*log(2)^2 + Pi^2 - 1)/24) * n^((1 - log(2))/4) / Pi^(n/2). For sufficiently large n 0.985... < a(n)/f(n) < 1.015...
a(n) ~ exp(-1/4) * QPochhammer(exp(-4)) * QPochhammer(-n*exp(-1)/2, exp(-4)) * 2^(n^2) / Pi^(n/2) if n is even and a(n) ~ exp(-1/4) * QPochhammer(exp(-4)) * QPochhammer(-n*exp(-3)/2, exp(-4)) * sqrt(n) * 2^(n^2 - 1/2) / Pi^(n/2) if n is odd.

A355464 Expansion of Sum_{k>=0} x^k/(1 - k^k * x)^(k+1).

Original entry on oeis.org

1, 2, 4, 17, 210, 9217, 1399298, 811229225, 2071392232962, 20710319937493889, 1137259214532706572162, 255141201504146525745627265, 348787971214016591166179037803522, 2262996819897931095524655885144485185409
Offset: 0

Views

Author

Seiichi Manyama, Jul 03 2022

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, x^k/(1-k^k*x)^(k+1)))
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, exp(k^k*x)*x^k/k!)))
    
  • PARI
    a(n) = sum(k=0, n, k^(k*(n-k))*binomial(n, k));

Formula

E.g.f.: Sum_{k>=0} exp(k^k * x) * x^k/k!.
a(n) = Sum_{k=0..n} k^(k*(n-k)) * binomial(n,k).

A355493 Expansion of Sum_{k>=0} (k^3 * x)^k/(1 - x)^(k+1).

Original entry on oeis.org

1, 2, 67, 19879, 16856337, 30601661681, 101743314190033, 559257425236996361, 4726837695171258085569, 58192258417571877186113281, 1000581709943568968705788233921, 23236157618902718144948494353385025, 709080642850925779233576351761544968833
Offset: 0

Views

Author

Seiichi Manyama, Jul 04 2022

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^3*x)^k/(1-x)^(k+1)))
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(x)*sum(k=0, N, (k^3*x)^k/k!)))
    
  • PARI
    a(n) = sum(k=0, n, k^(3*k)*binomial(n, k));

Formula

E.g.f.: exp(x) * Sum_{k>=0} (k^3 * x)^k/k!.
a(n) = Sum_{k=0..n} k^(3*k) * binomial(n,k).

A135749 a(n) = Sum_{k=0..n} binomial(n,k)*(n-k)^k*k^k.

Original entry on oeis.org

1, 1, 3, 19, 217, 3821, 95761, 3214975, 137501505, 7226764921, 455941716481, 33983083953611, 2954163633223969, 296027886705639973, 33823026186790043841, 4363561123325076879991, 630392564294402819207041
Offset: 0

Views

Author

Paul D. Hanna, Nov 27 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[n,k](n-k)^k k^k,{k,n}],{n,0,20}]+1 (* Harvey P. Dale, Oct 08 2012 *)
  • PARI
    a(n)=sum(k=0,n,binomial(n,k)*(n-k)^k*k^k)
    
  • PARI
    a(n)=n!*polcoeff(sum(k=0,n,exp((n-k)*k*x +x*O(x^n))*x^k/k!),n)

Formula

a(n) = n!*[x^n] Sum_{k=0..n} exp((n-k)*x)^k * x^k/k!.

A277453 a(n) = Sum_{k=0..n} binomial(n,k) * 2^k * n^k * k!.

Original entry on oeis.org

1, 3, 41, 1531, 111393, 13262051, 2336744233, 570621092091, 184341785557121, 76092709735150723, 39064090158380196201, 24408768326642565035963, 18237590837527919131499041, 16056004231253610384348995811, 16448689708899063469247204152553
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 16 2016

Keywords

Crossrefs

Programs

  • Mathematica
    Flatten[{1, Table[Sum[Binomial[n, k]*2^k*n^k*k!, {k, 0, n}], {n, 1, 20}]}]

Formula

a(n) = exp(1/(2*n)) * 2^n * n^n * Gamma(n+1, 1/(2*n)).
a(n) ~ 2^n * n^n * n!.

A308863 Expansion of e.g.f. (1 + LambertW(-x))/(1 + 2*LambertW(-x)).

Original entry on oeis.org

1, 1, 6, 57, 736, 11985, 235296, 5403937, 142073856, 4206560769, 138483596800, 5017244970441, 198363105460224, 8498001799768273, 392127481640165376, 19388814120804416625, 1022681739669784231936, 57317273018414456262273, 3401527253966521309200384
Offset: 0

Views

Author

Ilya Gutkovskiy, Jun 29 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 18; CoefficientList[Series[(1 + LambertW[-x])/(1 + 2 LambertW[-x]), {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, k] k^k a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 18}]

Formula

E.g.f.: 1 / (1 - Sum_{k>=1} k^k*x^k/k!).
a(0) = 1; a(n) = Sum_{k=1..n} binomial(n,k) * k^k * a(n-k).
a(n) ~ sqrt(Pi) * 2^(n - 3/2) * n^(n + 1/2) / exp(n/2). - Vaclav Kotesovec, Jun 29 2019

A110140 Binomial transform of n^n (with interpolated zeros).

Original entry on oeis.org

1, 1, 2, 4, 11, 31, 103, 351, 1321, 5113, 21201, 90465, 406621, 1879021, 9051309, 44754061, 229059633, 1201271409, 6488957521, 35853950609, 203303964341, 1177299817093, 6976709899853, 42161309544541, 260154190137865
Offset: 0

Views

Author

Paul Barry, Jul 13 2005

Keywords

Comments

Binomial transform of 1,0,1,0,4,0,27,....

Crossrefs

Programs

  • Mathematica
    Table[1 + Sum[Binomial[n, k]*(k/2)^(k/2)*(1 + (-1)^k)/2, {k, 1, n}], {n, 0, 30}] (* Vaclav Kotesovec, Oct 30 2017 *)

Formula

a(n)=sum{k=0..n, C(n, k)(k/2)^(k/2)*(1+(-1)^k)/2}
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