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 1-5 of 5 results.

A085686 Inverse Euler transform of Bell numbers.

Original entry on oeis.org

1, 1, 3, 9, 34, 135, 610, 2965, 15612, 87871, 526274, 3334850, 22270254, 156172689, 1146640394, 8791424549, 70227355786, 583283741066, 5027823752930, 44903579626132, 414877600876638, 3959945232723603, 38996757506464858, 395749369598406027, 4134132167178705732
Offset: 1

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Author

N. J. A. Sloane, Jul 18 2003

Keywords

Crossrefs

Programs

  • Maple
    read transforms; A := series(exp(exp(x)-1),x,60); A000110 := n->n!*coeff(A,x,n); [seq(A000110(i),i=1..30)]; EULERi(%);
    # The function EulerInvTransform is defined in A358451.
    a := EulerInvTransform(combinat:-bell):
    seq(a(n), n = 1..25); # Peter Luschny, Nov 21 2022
  • Mathematica
    n=24; eq[0] = Rest[ Thread[ CoefficientList[ 1 + Series[ Sum[ BellB[k]*x^k, {k, 1, n}] - Product[1/(1-x^k)^a[k], {k, 1, n}], {x, 0, n}], x] == 0]]; s[1] = First[ Solve[ First[eq[0]], a[1]]]; Do[eq[k] = Rest[eq[k-1]] /. s[k]; s[k+1] = First[ Solve[ First[eq[k]], a[k+1]]], {k, 1, n-1}]; Table[a[k], {k, 1, n}] /. Flatten[Table[s[k], {k, 1, n}]] (* Jean-François Alcover, Jul 26 2011 *)
    bb = Array[BellB, n = 25]; s = {}; For[i = 1, i <= n, i++, AppendTo[s, i* bb[[i]] - Sum[s[[d]]*bb[[i-d]], {d, i-1}]]]; Table[Sum[If[Divisible[i, d], MoebiusMu[i/d], 0]*s[[d]], {d, 1, i}]/i, {i, n}] (* Jean-François Alcover, Apr 15 2016 *)

A305850 Weigh transform of the Bell numbers (A000110).

Original entry on oeis.org

1, 1, 2, 7, 21, 78, 305, 1304, 6007, 29854, 159012, 904986, 5479078, 35150263, 238033523, 1695554145, 12663533586, 98881246850, 805128085616, 6820302066048, 59983405937707, 546690232627480, 5154757226832625, 50208266917662433, 504482106565647708
Offset: 0

Views

Author

Alois P. Heinz, Jun 11 2018

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 1,
          add(binomial(n-1, j-1)*g(n-j), j=1..n))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(g(i), j)*b(n-i*j, i-1), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 1,
         Sum[Binomial[n - 1, j - 1]*g[n - j], {j, 1, n}]];
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0,
         Sum[Binomial[g[i], j]*b[n - i*j, i - 1], {j, 0, n/i}]]];
    a[n_] := b[n, n];
    Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 12 2022, after Alois P. Heinz *)

Formula

G.f.: Product_{k>=1} (1+x^k)^Bell(k).

A305853 Inverse Weigh transform of the Fubini numbers (ordered Bell numbers, A000670).

Original entry on oeis.org

1, 3, 10, 62, 446, 3975, 41098, 484152, 6390488, 93419965, 1498268466, 26159940522, 494036061550, 10035451747919, 218207845446062, 5057251219752612, 124462048466812950, 3241773988594489244, 89093816361187396674, 2576652694087236419386, 78224564280680539732266
Offset: 1

Views

Author

Alois P. Heinz, Jun 11 2018

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 1,
          add(g(n-j)*binomial(n, j), j=1..n))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(a(i), j)*b(n-i*j, i-1), j=0..n/i)))
        end:
    a:= proc(n) option remember; g(n)-b(n, n-1) end:
    seq(a(n), n=1..30);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 1,
        Sum[g[n - j] Binomial[n, j], {j, 1, n}]];
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0,
        Sum[Binomial[a[i], j] b[n - i j, i - 1], {j, 0, n/i}]]];
    a[n_] := a[n] = g[n] - b[n, n - 1];
    a /@ Range[1, 30] (* Jean-François Alcover, Dec 21 2020, after Alois P. Heinz *)

Formula

Product_{k>=1} (1+x^k)^a(k) = Sum_{n>=0} A000670(n) * x^n.
a(n) ~ n! / (2 * log(2)^(n+1)). - Vaclav Kotesovec, Sep 10 2019

A353831 Product_{n>=1} (1 + a(n)*x^n) = Sum_{n>=0} Bell(n)*x^n, where Bell = A000110.

Original entry on oeis.org

1, 2, 3, 12, 34, 139, 610, 3046, 15604, 88460, 526274, 3344037, 22270254, 156359026, 1146627256, 8796070308, 70227355786, 583404596184, 5027823752930, 44907492540298, 414877525216196, 3960083715148092, 38996757506464858, 395754951565246801, 4134132167169618654, 44409616948511664062
Offset: 1

Views

Author

Ilya Gutkovskiy, May 11 2022

Keywords

Crossrefs

Programs

  • Mathematica
    A[m_, n_] := A[m, n] = Which[m == 1, BellB[n], m > n >= 1, 0, True, A[m - 1, n] - A[m - 1, m - 1] A[m, n - m + 1]]; a[n_] := A[n, n]; a /@ Range[1, 26]

A353944 Product_{n>=1} 1 / (1 - a(n)*x^n) = Sum_{n>=0} Bell(n)*x^n, where Bell = A000110.

Original entry on oeis.org

1, 1, 3, 9, 34, 132, 610, 2929, 15604, 87310, 526274, 3325946, 22270254, 155986944, 1146627256, 8787134873, 70227355786, 583161239732, 5027823752930, 44899767806134, 414877525216196, 3959806750825202, 38996757506464858, 395743830189684984, 4134132167169618654, 44409120984298440176
Offset: 1

Views

Author

Ilya Gutkovskiy, May 12 2022

Keywords

Crossrefs

Programs

  • Mathematica
    A[m_, n_] := A[m, n] = Which[m == 1, BellB[n], m > n >= 1, 0, True, A[m - 1, n] - A[m - 1, m - 1] A[m - 1, n - m + 1]]; a[n_] := A[n, n]; a /@ Range[1, 26]

Formula

Conjecture: a(n) ~ Bell(n). - Vaclav Kotesovec, May 12 2022
Showing 1-5 of 5 results.