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 1-3 of 3 results.

A032299 "EFJ" (unordered, size, labeled) transform of 1,2,3,4,...

Original entry on oeis.org

1, 1, 2, 9, 16, 85, 516, 1519, 6280, 45441, 431740, 1394371, 8370924, 43960657, 459099018, 6135631545, 23813007376, 150537761905, 1029390040764, 7519458731131, 101693768415220, 1909742186139921, 8269148260309882, 60924484457661793, 417027498430063800
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    mmax = 25;
    egf = Product[1 + x^m/(m - 1)!, {m, 1, mmax}] + O[x]^mmax;
    CoefficientList[egf, x] * Range[0, mmax - 1]! (* Jean-François Alcover, Sep 23 2019 *)
  • PARI
    seq(n)={Vec(serlaplace(prod(k=1, n, 1 + k*x^k/k! + O(x*x^n))))} \\ Andrew Howroyd, Sep 11 2018

Formula

E.g.f.: Product_{m>0} (1+x^m/(m-1)!). - Vladeta Jovovic, Nov 26 2002
E.g.f.: exp(Sum_{k>=1} Sum_{j>=1} (-1)^(k+1)*x^(j*k)/(k*((j - 1)!)^k)). - Ilya Gutkovskiy, Sep 13 2018

Extensions

a(0)=1 prepended and terms a(23) and beyond from Andrew Howroyd, Sep 11 2018

A319218 Expansion of e.g.f. Product_{k>=1} (1 - x^k/(k - 1)!).

Original entry on oeis.org

1, -1, -2, 3, 8, 75, -216, -175, -3816, -36225, 189800, 325149, 2375460, 25547951, 386162126, -3290670825, -6316583056, -59290501809, -310987223208, -4836373835707, -86500419684420, 1119358992256239, 3043733432729198, 26408738842522959, 169835931388147464
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 13 2018

Keywords

Crossrefs

Programs

  • Maple
    seq(n!*coeff(series(mul((1 - x^k/(k - 1)!),k=1..100),x=0,25),x,n),n=0..24); # Paolo P. Lava, Jan 09 2019
  • Mathematica
    nmax = 24; CoefficientList[Series[Product[(1 - x^k/(k - 1)!), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
    nmax = 24; CoefficientList[Series[Exp[-Sum[Sum[x^(j k)/(k (j - 1)!^k), {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
    a[n_] := a[n] = If[n == 0, 1, (n - 1)! Sum[Sum[-d (d - 1)!^(-k/d), {d, Divisors[k]}] a[n - k]/(n - k)!, {k, 1, n}]]; Table[a[n], {n, 0, 24}]

Formula

E.g.f.: exp(-Sum_{k>=1} Sum_{j>=1} x^(j*k)/(k*((j - 1)!)^k)).

A319219 Expansion of e.g.f. Product_{k>=1} 1/(1 + x^k/(k - 1)!).

Original entry on oeis.org

1, -1, 0, -3, 32, -105, 204, -3325, 52408, -376425, 1304180, -25766301, 659066484, -6675505837, 30765540974, -893416597515, 29169795361424, -380344619169729, 2379504317523300, -84225906785770525, 3388223174832010540, -55107296201168047221, 422923168260105913070
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 13 2018

Keywords

Crossrefs

Programs

  • Maple
    seq(n!*coeff(series(mul(1/(1 + x^k/(k - 1)!),k=1..100),x=0,23),x,n),n=0..22); # Paolo P. Lava, Jan 09 2019
  • Mathematica
    nmax = 22; CoefficientList[Series[Product[1/(1 + x^k/(k - 1)!), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
    nmax = 22; CoefficientList[Series[Exp[Sum[Sum[x^(j k)/(k (-(j - 1)!)^k), {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
    a[n_] := a[n] = If[n == 0, 1, (n - 1)! Sum[Sum[d (-(d - 1)!)^(-k/d), {d, Divisors[k]}] a[n - k]/(n - k)!, {k, 1, n}]]; Table[a[n], {n, 0, 22}]

Formula

E.g.f.: exp(Sum_{k>=1} Sum_{j>=1} x^(j*k)/(k*(-(j - 1)!)^k)).
Showing 1-3 of 3 results.