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.

A039692 Jabotinsky-triangle related to A039647.

Original entry on oeis.org

1, 3, 1, 8, 9, 1, 42, 59, 18, 1, 264, 450, 215, 30, 1, 2160, 4114, 2475, 565, 45, 1, 20880, 43512, 30814, 9345, 1225, 63, 1, 236880, 528492, 420756, 154609, 27720, 2338, 84, 1, 3064320, 7235568, 6316316, 2673972, 594489, 69552, 4074, 108, 1
Offset: 1

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Author

Keywords

Comments

Triangle gives the nonvanishing entries of the Jabotinsky matrix for F(z)= A(z)/z = 1/(1-z-z^2) where A(z) is the g.f. of the Fibonacci numbers A000045. (Notation of F(z) as in Knuth's paper.)
E(n,x) := Sum_{m=1..n} a(n,m)*x^m, E(0,x)=1, are exponential convolution polynomials: E(n,x+y) = Sum_{k=0..n} binomial(n,k)*E(k,x)*E(n-k,y) (cf. Knuth's paper with E(n,x)= n!*F(n,x)).
E.g.f. for E(n,x): (1 - z - z^2)^(-x).
Explicit a(n,m) formula: see Knuth's paper for f(n,m) formula with f(k)= A039647(n).
E.g.f. for the m-th column sequence: ((-log(1 - z - z^2))^m)/m!.
Also the Bell transform of n!*(F(n)+F(n+2)), F(n) the Fibonacci numbers. For the definition of the Bell transform see A264428 and the link. - Peter Luschny, Jan 16 2016

Examples

			1;
3, 1;
8, 9, 1;
42, 59, 18, 1;
264, 450, 215, 30, 1;
		

Crossrefs

Cf. A039647, A000032, A000045. Another version of this triangle is in A194938.

Programs

  • Maple
    A000032 := proc(n) option remember; coeftayl( (2-x)/(1-x-x^2),x=0,n) ; end: A039647 := proc(n) (n-1)!*A000032(n) ; end: A039692 := proc(n,m) option remember ; if m = 1 then A039647(n) ; else add( binomial(n-1,j-1)*A039647(j)*procname(n-j,m-1),j=1..n-m+1) ; fi; end: # R. J. Mathar, Jun 01 2009
  • Mathematica
    t[n_, m_] := n!*Sum[StirlingS1[k, m]*Binomial[k, n-k]*(-1)^(k+m)/k!, {k, m, n}]; Table[t[n, m], {n, 1, 9}, {m, 1, n}] // Flatten (* Jean-François Alcover, Jun 21 2013, after Vladimir Kruchinin *)
  • Maxima
    T(n,m) := n!*sum((stirling1(k,m)*binomial(k,n-k))*(-1)^(k+m)/k!,k,m,n); /* Vladimir Kruchinin, Mar 26 2013 */
    
  • PARI
    T(n,m) = n!*sum(k=m,n, (stirling(k,m,1)*binomial(k,n-k))*(-1)^(k+m)/k!);
    for(n=1,10,for(k=1,n,print1(T(n,k),", "));print());
    /* Joerg Arndt, Mar 27 2013 */
    
  • Sage
    # uses[bell_matrix from A264428]
    # Adds 1,0,0,0, ... as column 0 to the left side of the triangle.
    bell_matrix(lambda n: factorial(n)*(fibonacci(n)+fibonacci(n+2)), 8) # Peter Luschny, Jan 16 2016

Formula

a(n, 1)= A039647(n)=(n-1)!*L(n), L(n) := A000032(n) (Lucas); a(n, m) = Sum_{j=1..n-m+1} binomial(n-1, j-1)*A039647(j)*a(n-j, m-1), n >= m >= 2.
Conjectured row sums: sum_{m=1..n} a(n,m) = A005442(n). - R. J. Mathar, Jun 01 2009
T(n,m) = n! * Sum_{k=m..n} stirling1(k,m)*binomial(k,n-k)*(-1)^(k+m)/k!. - Vladimir Kruchinin, Mar 26 2013

A331339 E.g.f.: 1 / (1 + log(1 - x - x^2)).

Original entry on oeis.org

1, 1, 5, 32, 292, 3294, 44918, 714468, 13002456, 266275200, 6060498672, 151750887936, 4145522908272, 122690391196944, 3910569680464848, 133549150323123744, 4864927063250290176, 188297220693251438208, 7716800776602560577408
Offset: 0

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Author

Ilya Gutkovskiy, Jan 14 2020

Keywords

Crossrefs

Programs

  • Maple
    A331339 := proc(n)
        option remember;
        if n = 0 then
            1;
        else
            add(binomial(n,k)*(k-1)!*A000204(k)*procname(n-k),k=1..n) ;
        end if;
    end proc:
    seq(A331339(n),n=0..42) ; # R. J. Mathar, Aug 20 2021
  • Mathematica
    nmax = 18; CoefficientList[Series[1/(1 + Log[1 - x - x^2]), {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, k] (k - 1)! LucasL[k] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 18}]

Formula

a(0) = 1; a(n) = Sum_{k=1..n} binomial(n,k) * (k - 1)! * Lucas(k) * a(n-k).
a(n) ~ n! * 2^(n+1) * exp(n/2) / (sqrt(5*exp(1) - 4) * (sqrt(5*exp(1) - 4) - exp(1/2))^(n+1)). - Vaclav Kotesovec, Jan 26 2020

A039929 Second column of Fibonacci Jabotinsky-triangle A039692.

Original entry on oeis.org

0, 1, 9, 59, 450, 4114, 43512, 528492, 7235568, 110499696, 1862118720, 34342356960, 688092312960, 14886351037440, 345878769358080, 8590707803462400, 227153424885811200, 6371121297516595200
Offset: 1

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Comments

E.g.f.: (log(1-x-x^2))^2/2.

Crossrefs

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[Log[1-x-x^2]^2/2,{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Jun 11 2017 *)

Formula

a(n) = A039692(n, 2); a(n) = (n-1)!*sum(L(j)*L(n-j)/(n-j), j=1..n-1), n >= 2, L(n)= A000032(n) (Lucas).

A328286 Expansion of e.g.f. -log(1 - x - x^2/2).

Original entry on oeis.org

1, 2, 5, 21, 114, 780, 6390, 61110, 667800, 8210160, 112152600, 1685237400, 27624920400, 490572482400, 9381882510000, 192238348302000, 4201639474032000, 97572286427616000, 2399151995223984000, 62268748888378032000, 1701213856860117600000
Offset: 1

Views

Author

Ilya Gutkovskiy, Oct 11 2019

Keywords

Crossrefs

Cf. A009014, A039647, A080040, A080599 (exponential transform).

Programs

  • Maple
    b:= proc(n) b(n):= n! * (<<1|1>, <1/2|0>>^n)[1, 1] end:
    a:= proc(n) option remember; `if`(n=0, 0, b(n)-add(
          binomial(n, j)*j*b(n-j)*a(j), j=1..n-1)/n)
        end:
    seq(a(n), n=1..25);  # Alois P. Heinz, Oct 11 2019
  • Mathematica
    nmax = 21; CoefficientList[Series[-Log[1 - x - x^2/2], {x, 0, nmax}], x] Range[0, nmax]! // Rest
    FullSimplify[Table[(n - 1)! ((1 - Sqrt[3])^n + (1 + Sqrt[3])^n)/2^n, {n, 1, 21}]]
  • PARI
    my(x='x+O('x^25)); Vec(serlaplace(-log(1 - x - x^2/2))) \\ Michel Marcus, Oct 11 2019

Formula

a(n) = (n - 1)! * ((1 - sqrt(3))^n + (1 + sqrt(3))^n) / 2^n.
D-finite with recurrence +2*a(n) +2*(-n+1)*a(n-1) -(n-1)*(n-2)*a(n-2)=0. - R. J. Mathar, Aug 20 2021
Showing 1-4 of 4 results.