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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A336214 a(n) = Sum_{k=0..n} k^n * binomial(n,k)^n, with a(0)=1.

Original entry on oeis.org

1, 1, 8, 270, 41984, 30706250, 94770093312, 1336016204844832, 76829717664330940416, 19838680914222199482800274, 20521247958509575370600000000000, 94285013320530947020636486516362047300, 1715947732437668013396578734960052732361179136
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 12 2020

Keywords

Crossrefs

Programs

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

Formula

a(n) ~ c * exp(-1/4) * 2^(n^2 - n/2) * n^(n/2) / Pi^(n/2), where c = Sum_{k = -infinity..infinity} exp(-2*k*(k-1)) = exp(1/2) * sqrt(Pi/2) * EllipticTheta(3, -Pi/2, exp(-Pi^2/2)) = 2.036643566277677716389243890291939003151565... if n is even and c = Sum_{k = -infinity..infinity} exp(-2*k^2 + 1/2) = exp(1/2) * EllipticTheta(3, 0, exp(-2)) = 2.096087809957308346119920713317351288828811... if n is odd.
a(n) = n^n * A328812(n-1) for n > 0. - Seiichi Manyama, Jul 15 2020

A336828 a(n) = Sum_{k=0..n} binomial(n,k)^2 * k^n.

Original entry on oeis.org

1, 1, 8, 108, 2144, 56250, 1836792, 71799504, 3269445888, 169974711630, 9934458411800, 644825382429096, 46022332032100800, 3582265183110626740, 302002255041807372080, 27413749834141448520000, 2665789990569658618398720, 276477318687585566522176470
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 05 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[Binomial[n, k]^2 k^n, {k, 0, n}], {n, 1, 17}]]
  • PARI
    a(n) = sum(k=0, n, binomial(n, k)^2*k^n); \\ Michel Marcus, Aug 05 2020

Formula

a(n) ~ c * d^n * (n-1)!, where d = (1 + 2*LambertW(exp(-1/2)/2)) / (4*LambertW(exp(-1/2)/2)^2) = 6.476217542109791521947605963458797355564... and c = 0.21617818094152997942246965143216887599763501682724844713834495... - Vaclav Kotesovec, Feb 20 2021

A345876 a(n) = Sum_{k=0..n} binomial(2*n, n-k) * k^n.

Original entry on oeis.org

1, 1, 8, 90, 1408, 28350, 697344, 20264244, 679313408, 25805186550, 1095482736640, 51397070440716, 2640925289349120, 147491783753286700, 8895880971425939456, 576279075821454657000, 39905347440408027725824, 2941534126495441574472870, 229966392623413457628168192
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 03 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[Binomial[2*n, n-k]*k^n, {k, 0, n}], {n, 1, 20}]]
  • PARI
    a(n) = sum(k=0, n, binomial(2*n, n-k) * k^n); \\ Michel Marcus, Oct 03 2021

Formula

a(n) ~ 2^(2*n + 1/2) * r^(n+1) * n^n / (sqrt(1 + r^2) * exp(n) * (1 - r^2)^n), where r = 0.647918229029602749602061258113970414114660380467168496836586... is the positive root of the equation (1 + r) = (1 - r)*exp(1/r).

A362702 Expansion of e.g.f. 1/(1 + LambertW(-x^2 * exp(x))).

Original entry on oeis.org

1, 0, 2, 6, 60, 500, 6150, 81522, 1300376, 23024808, 459915210, 10104914270, 243652575012, 6378414900156, 180405368976014, 5478759958122570, 177868544365861680, 6146407749811022672, 225262698504062963346, 8727083181657584963766
Offset: 0

Views

Author

Seiichi Manyama, Apr 30 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1+lambertw(-x^2*exp(x)))))

Formula

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

A074932 Row sums of unsigned triangle A075513.

Original entry on oeis.org

1, 3, 18, 170, 2200, 36232, 725200, 17095248, 463936896, 14246942336, 488428297984, 18491942300416, 766293946203136, 34498781924766720, 1676731077272217600, 87501958444207351808, 4880017252828686155776
Offset: 1

Views

Author

Wolfdieter Lang, Oct 02 2002

Keywords

Examples

			E.g.f.: A(x) = x + 3*x^2/2! + 18*x^3/3! + 170*x^4/4! + 2200*x^5/5! +...
where exp(A(x)) = 1 + x + 4*x^2/2! + 28*x^3/3! + 288*x^4/4! + 3936*x^5/5! + 67328*x^6/6! +...+ A201595(n)*x^n/n! +...
		

Crossrefs

Cf. A201595.

Programs

  • Mathematica
    Rest[CoefficientList[Series[Log[x-LambertW[-x*Exp[x]]]-Log[2*x], {x, 0, 20}], x]* Range[0, 20]!] (* Vaclav Kotesovec, Dec 04 2012 *)
    a[n_] := Sum[Binomial[n-1, k]*(k+1)^(n-1), {k, 0, n-1}]; Table[a[n], {n, 1, 17}] (* Jean-François Alcover, Jul 09 2013, after Paul D. Hanna *)
  • PARI
    {a(n)=sum(k=0,n-1,binomial(n-1,k)*(k+1)^(n-1))} \\ Paul D. Hanna, Aug 02 2012
    
  • PARI
    {a(n)=local(A201595=serreverse(x-x*tanh(x+x^2*O(x^n)))/x);n!*polcoeff(log(A201595), n)} \\ Paul D. Hanna, Aug 02 2012
    
  • PARI
    {a(n) = my(A); if( n<0, 0, A = O(x); for(k=1, n, A = log( (1 + exp( 2*x * exp(A))) / 2 )); n! * polcoeff(A, n))}; /* Michael Somos, Apr 10 2018 */

Formula

a(n) = sum(|A075513(n, m)|, m=0..n-1) = sum(binomial(n-1, m)*(m+1)^(n-1), m=0..n-1), n>=1.
E.g.f.: log(G(x)) where G(x) = (1 + exp(2*x*G(x)))/2 is the e.g.f. of A201595. - Paul D. Hanna, Aug 02 2012
E.g.f: log(x-LambertW(-x*exp(x)))-log(2*x). - Vaclav Kotesovec, Dec 04 2012
a(n) ~ n!/(sqrt(2*Pi*(1+LambertW(exp(-1))))*n^(3/2)*LambertW(exp(-1))^n). - Vaclav Kotesovec, Dec 04 2012
a(n) = A072034(n)/n. - Vladimir Reshetnikov, Nov 09 2016
O.g.f.: Sum_{k>=1} k^(k-1)*x^k/(1 - k*x)^k. - Ilya Gutkovskiy, Oct 09 2018

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.

A343928 a(n) = Sum_{k=0..n} (k!)^n * binomial(n,k).

Original entry on oeis.org

1, 2, 7, 244, 337061, 24923091206, 139331988275478727, 82607113404338664216300296, 6984967577834038055008791270166057993, 109110690950275218023122492287310115968068596613130, 395940866518366059877297056617763923418318903997411043997258716171
Offset: 0

Views

Author

Seiichi Manyama, May 04 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Sum[(k!)^n * Binomial[n, k], {k, 0, n} ]; Array[a, 11, 0] (* Amiram Eldar, May 04 2021 *)
  • PARI
    a(n) = sum(k=0, n, k!^n*binomial(n, k));

Formula

a(n) = [x^n] Sum_{k>=0} (k!)^n * x^k/(1 - x)^(k+1).
a(n) = n! * [x^n] exp(x) * Sum_{k>=0} (k!)^(n-1) * x^k.

A355470 Expansion of Sum_{k>=0} (k^3 * x)^k/(1 - k^3 * x)^(k+1).

Original entry on oeis.org

1, 1, 66, 21222, 18927560, 36030104000, 125486684755152, 722272396672485568, 6391048590559497227904, 82362961035803105954736768, 1482370265813455598541301007360, 36031982428595760278113744699088384, 1150873035676373345725887922070318410752
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, (k^3*x)^k/(1-k^3*x)^(k+1)))
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(1+sum(k=1, N, exp(k^3*x)*(k^3*x)^k/k!)))
    
  • PARI
    a(n) = sum(k=0, n, k^(3*n)*binomial(n, k));

Formula

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

A215080 T(n,k) = Sum_{j=0..k} (k-j)^n * binomial(n,j).

Original entry on oeis.org

1, 0, 1, 0, 1, 6, 0, 1, 11, 54, 0, 1, 20, 151, 680, 0, 1, 37, 413, 2569, 11000, 0, 1, 70, 1128, 9450, 52431, 217392, 0, 1, 135, 3104, 34416, 243255, 1251921, 5076400, 0, 1, 264, 8637, 125248, 1113027, 7025016, 34282879, 136761984, 0, 1, 521, 24327, 457807, 5064143, 38811015, 225930121, 1059812993, 4175432064, 0, 1, 1034, 69334, 1685266, 23031680, 212609518, 1465077802, 8026643702, 36519075583, 142469423360
Offset: 0

Views

Author

Olivier Gérard, Aug 02 2012

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,   6;
  0, 1,  11,   54;
  0, 1,  20,  151,    680;
  0, 1,  37,  413,   2569,   11000;
  0, 1,  70, 1128,   9450,   52431,  217392;
  0, 1, 135, 3104,  34416,  243255, 1251921,  5076400;
  0, 1, 264, 8637, 125248, 1113027, 7025016, 34282879, 136761984;
  ...
		

Crossrefs

Row sums give 215077 (binomial convolution of descending powers).
Main diagonal gives A072034.

Programs

  • Mathematica
    Flatten[Table[Table[Sum[(k - j)^n*Binomial[n, j], {j, 0, k}], {k, 0, n}], {n, 0, 10}], 1]

Formula

T(n,k) = sum( (k-j)^n * binomial(n,j), j=0..k).

A341815 a(n) = Sum_{k=0..n} binomial(n,k)^3 * k^n.

Original entry on oeis.org

1, 1, 12, 270, 8960, 406250, 23293872, 1617774592, 132075970560, 12397121784954, 1315528361642000, 155743010418063860, 20351866171905066240, 2909818652684404979440, 451849287590990124662400, 75730203998219999637000000, 13625593688459657260608782336, 2619521322904712777031960349850
Offset: 0

Views

Author

Vaclav Kotesovec, Feb 20 2021

Keywords

Comments

For m>0, Sum_{k=0..n} binomial(n,k)^m * k^n ~ c(m) * d^n * n! / n^(m/2), where d = (1 + m*LambertW(exp(-1/m)/m))^(m-1) / (m^m * LambertW(exp(-1/m)/m)^m) and c(m) is a constant independent of n.

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[k^n * Binomial[n, k]^3, {k, 0, n}], {n, 1, 20}]]

Formula

a(n) ~ c * d^n * n! / n^(3/2), where d = (1 + 3*LambertW(exp(-1/3)/3))^2 / (27 * LambertW(exp(-1/3)/3)^3) = 12.3645613141726293982008517178673172577947617775... and c = 0.143687082995832067469009730530027989920523409582173778129054767279...
Previous Showing 11-20 of 36 results. Next