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 11-14 of 14 results.

A143631 Let A(0) = 1, B(0) = 0 and C(0) = 0. Let A(n+1) = - Sum_{k = 0..n} binomial(n,k)*C(k), B(n+1) = Sum_{k = 0..n} binomial(n,k)*A(k) and C(n+1) = Sum_{k = 0..n} binomial(n,k)*B(k). This entry gives the sequence B(n).

Original entry on oeis.org

0, 1, 1, 1, 0, -9, -64, -348, -1672, -7307, -28225, -81817, 14191, 3143571, 38184875, 353727284, 2916494333, 22260343389, 157677357255, 1007259846130, 5241783274713, 12146415146776, -210638381350012, -4813155361775252
Offset: 0

Views

Author

Peter Bala, Sep 05 2008

Keywords

Comments

The other sequences are A(n) = A143628(n) and C(n) = A143630(n). Compare with A121867 and A121868. See also A143816.

Crossrefs

Programs

  • Maple
    # Compare with A143816
    #
    M:=24: a:=array(0..100): b:=array(0..100): c:=array(0..100):
    a[0]:=1: b[0]:=0: c[0]:=0:
    for n from 1 to M do
    a[n]:= -add(binomial(n-1,k)*c[k], k=0..n-1);
    b[n]:= add(binomial(n-1,k)*a[k], k=0..n-1);
    c[n]:= add(binomial(n-1,k)*b[k], k=0..n-1);
    end do:
    A143631:=[seq(b[n], n=0..M)];
  • Mathematica
    m = 23; a[0] = 1; b[0] = 0; c[0] = 0; For[n = 1, n <= m, n++, b[n] = -Sum[Binomial[n - 1, k]*a[k], {k, 0, n - 1}]; c[n] = Sum[Binomial[n - 1, k]*b[k], {k, 0, n - 1}];  a[n] = Sum[Binomial[n - 1, k]*c[k], {k, 0, n - 1}]]; A143631 = Table[ -b[n], {n, 0, m}] (* Jean-François Alcover, Mar 06 2013, after Maple *)
  • PARI
    Bell_poly(n, x) = exp(-x)*suminf(k=0, k^n*x^k/k!);
    a(n) = my(w=(-1+sqrt(3)*I)/2); -round(Bell_poly(n, -1)+w^2*Bell_poly(n, -w)+w*Bell_poly(n, -w^2))/3; \\ Seiichi Manyama, Oct 15 2022

Formula

a(n) = A143629(n) + A143630(n).
From Seiichi Manyama, Oct 15 2022: (Start)
a(n) = Sum_{k = 0..floor((n-1)/3)} (-1)^k * Stirling2(n,3*k+1).
a(n) = -( Bell_n(-1) + w^2 * Bell_n(-w) + w * Bell_n(-w^2) )/3, where Bell_n(x) is n-th Bell polynomial and w = exp(2*Pi*i/3). (End)

A143625 Decimal expansion of the constant E_3(0) := Sum_{n >= 0} (-1)^floor(n/3)/n! = 1 + 1/1! + 1/2! - 1/3! - 1/4! - 1/5! + + + - - - ... .

Original entry on oeis.org

2, 2, 8, 4, 9, 4, 2, 3, 8, 2, 4, 0, 9, 6, 3, 5, 2, 0, 8, 9, 9, 9, 0, 5, 0, 0, 1, 9, 2, 6, 3, 0, 8, 2, 7, 0, 2, 1, 6, 1, 5, 1, 3, 2, 6, 2, 9, 9, 4, 9, 5, 8, 9, 7, 8, 5, 9, 8, 2, 8, 8, 9, 8, 0, 0, 3, 7, 3, 7, 1, 0, 1, 5, 7, 5, 1, 9, 7, 3, 4, 5, 9, 4, 0, 3, 7, 4, 4, 9, 5, 1, 2, 5, 2, 4, 6, 3, 4, 4, 8, 8
Offset: 1

Views

Author

Peter Bala, Aug 30 2008

Keywords

Comments

Define E_3(n) = Sum_{k >= 0} (-1)^floor(k/3)*k^n/k! = 0^n/0! + 1^n/1! + 2^n/2! - 3^n/3! - 4^n/4! - 5^n/5! + + + - - - ... for n = 0,1,2,... . It is easy to see that E_3(n+3) = 3*E_3(n+2) - 2*E_3(n+1) - Sum_{i = 0..n} 3^i*binomial(n,i) * E_3(n-i) for n >= 0. Thus E_3(n) is an integral linear combination of E_3(0), E_3(1) and E_3(2). See the examples below.
The decimal expansions of E_3(1) and E_3(2) are given in A143626 and A143627. Compare with A143623 and A143624.
E_3(n) as linear combination of E_3(i), i = 0..2.
=======================================
..E_3(n)..|....E_3(0)...E_3(1)...E_3(2)
=======================================
..E_3(3)..|.....-1.......-2........3...
..E_3(4)..|.....-6.......-7........7...
..E_3(5)..|....-25......-23.......14...
..E_3(6)..|....-89......-80.......16...
..E_3(7)..|...-280.....-271......-77...
..E_3(8)..|...-700.....-750.....-922...
..E_3(9)..|...-380.....-647....-6660...
..E_3(10).|..13452....13039...-41264...
...
The columns are A143628, A143629 and A143630.

Examples

			2.284942382409635208999050...
		

References

  • Mohammad K. Azarian, A Generalization of the Climbing Stairs Problem, Mathematics and Computer Education Journal, Vol. 31, No. 1, pp. 24-28, Winter 1997.

Crossrefs

Programs

  • Mathematica
    RealDigits[ N[ (2*E^(3/2)*(Cos[Sqrt[3]/2] + Sqrt[3]*Sin[Sqrt[3]/2]) + 1)/(3*E), 105]][[1]] (* Jean-François Alcover, Nov 08 2012 *)

Extensions

Offset corrected by R. J. Mathar, Feb 05 2009

A143626 Decimal expansion of the constant E_3(1) := Sum_{k >= 0} (-1)^floor(k/3)*k/k! = 1/1! + 2/2! - 3/3! - 4/4! - 5/5! + + + - - - ... .

Original entry on oeis.org

1, 3, 0, 1, 5, 5, 9, 4, 9, 5, 9, 8, 2, 9, 7, 9, 6, 0, 2, 8, 4, 3, 0, 4, 2, 7, 0, 8, 2, 5, 5, 1, 9, 9, 2, 7, 4, 2, 3, 4, 9, 4, 6, 9, 7, 2, 9, 6, 4, 7, 7, 1, 7, 0, 0, 7, 4, 7, 5, 5, 3, 4, 1, 4, 2, 0, 7, 7, 2, 4, 0, 7, 2, 9, 9, 2, 5, 4, 4, 6, 4, 4, 4, 3, 7, 4, 5, 3, 0, 1, 0, 3, 2, 0, 4, 9, 5, 8, 3, 2, 7
Offset: 1

Views

Author

Peter Bala, Aug 30 2008

Keywords

Comments

Define E_3(n) = Sum_{k >= 0} (-1)^floor(k/3)*k^n/k! = 0^n/0! + 1^n/1! + 2^n/2! - 3^n/3! - 4^n/4! - 5^n/5! + + + - - - ... for n = 0,1,2,... . It is easy to see that E_3(n+3) = 3*E_3(n+2) - 2*E_3(n+1) - Sum_{i = 0..n} 3^i*binomial(n,i) * E_3(n-i) for n >= 0. Thus E_3(n) is an integral linear combination of E_3(0), E_3(1) and E_3(2). See the examples below.
The decimal expansions of E_3(0) and E_3(2) are given in A143635 and A143627. Compare with A143623 and A143624.
E_3(n) as linear combination of E_3(i), i = 0..2.
=======================================
..E_3(n)..|....E_3(0)...E_3(1)...E_3(2)
=======================================
..E_3(3)..|.....-1.......-2........3...
..E_3(4)..|.....-6.......-7........7...
..E_3(5)..|....-25......-23.......14...
..E_3(6)..|....-89......-80.......16...
..E_3(7)..|...-280.....-271......-77...
..E_3(8)..|...-700.....-750.....-922...
..E_3(9)..|...-380.....-647....-6660...
..E_3(10).|..13452....13039...-41264...
...
The columns are A143628, A143629 and A143630.

Examples

			1.3015594959829796028430427
		

Crossrefs

Programs

  • Mathematica
    RealDigits[ N[ (4*E^(3/2)*Cos[Sqrt[3]/2] - 1)/(3*E), 105]][[1]] (* Jean-François Alcover, Nov 08 2012 *)

Extensions

Offset corrected by R. J. Mathar, Feb 05 2009

A143627 Decimal expansion of the constant E_3(2) := sum {k = 0.. inf} (-1)^floor(k/3)*k^2/k! = 1/1! + 2^2/2! - 3^2/3! - 4^2/4! - 5^2/5! + + + - - - ... = 0.68605 60507 ... .

Original entry on oeis.org

6, 8, 6, 0, 5, 6, 0, 5, 0, 7, 2, 7, 7, 6, 6, 3, 1, 8, 2, 8, 2, 5, 5, 9, 1, 6, 7, 4, 0, 8, 7, 7, 6, 7, 1, 3, 7, 5, 4, 1, 9, 1, 8, 1, 3, 9, 6, 6, 3, 5, 2, 2, 5, 7, 4, 0, 4, 6, 5, 4, 6, 5, 0, 0, 7, 5, 5, 3, 8, 6, 2, 5, 9, 7, 8, 0, 1, 5, 6, 3, 2, 8, 2, 8, 3, 0, 8, 3, 4, 3, 7, 3, 4, 4, 4, 7, 8, 6, 0, 3
Offset: 0

Views

Author

Peter Bala, Aug 30 2008

Keywords

Comments

Define E_3(n) = sum {k = 0..inf} (-1)^floor(k/3)*k^n/k! = 0^n/0! + 1^n/1! + 2^n/2! - 3^n/3! - 4^n/4! - 5^n/5! + + + - - - ... for n = 0,1,2,... . It is easy to see that E_3(n+3) = 3*E_3(n+2) - 2*E_3(n+1) - sum {i = 0..n} 3^i*binomial(n,i) * E_3(n-i) for n >= 0. Thus E_3(n) is an integral linear combination of E_3(0), E_3(1) and E_3(2). See the examples below. The decimal expansions of E_3(0) and E_3(1) are given in A143625 and A143626. Compare with A143623 and A143624.

Examples

			E_3(n) as linear combination of E_3(i),
i = 0..2.
=======================================
..E_3(n)..|....E_3(0)...E_3(1)...E_3(2)
=======================================
..E_3(3)..|.....-1.......-2........3...
..E_3(4)..|.....-6.......-7........7...
..E_3(5)..|....-25......-23.......14...
..E_3(6)..|....-89......-80.......16...
..E_3(7)..|...-280.....-271......-77...
..E_3(8)..|...-700.....-750.....-922...
..E_3(9)..|...-380.....-647....-6660...
..E_3(10).|..13452....13039...-41264...
...
The columns are A143628, A143629 and A143630.
		

Crossrefs

Programs

  • Mathematica
    RealDigits[N[(8/3)*Sqrt[E]*Cos[Sqrt[3]/2] + (1/40)*(HypergeometricPFQ[{}, {7/3, 8/3}, -(1/27)] - 5*HypergeometricPFQ[{}, {5/3, 7/3}, -(1/27)]) - 2*Sqrt[E/3]*Sin[Sqrt[3]/2] - 5/(3*E), 105]][[1]] (* Jean-François Alcover, Nov 08 2012 *)

Extensions

Offset corrected by R. J. Mathar, Feb 05 2009
Previous Showing 11-14 of 14 results.