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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A143632 Table T(n,k), n>=0, k>=0, read by antidiagonals, where the e.g.f. for column k satisfies A_k(x) = exp(x*A_k(((x+1)^k-1)/k)) if k>0 and A_0(x) = exp(x*A_0(0)) = exp(x).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 3, 16, 1, 1, 1, 3, 19, 125, 1, 1, 1, 3, 22, 185, 1296, 1, 1, 1, 3, 25, 253, 2541, 16807, 1, 1, 1, 3, 28, 329, 4256, 45787, 262144, 1, 1, 1, 3, 31, 413, 6471, 96727, 1037359, 4782969, 1, 1, 1, 3, 34, 505, 9216, 175747, 2828274, 28649553, 100000000, 1
Offset: 0

Views

Author

Alois P. Heinz, Aug 27 2008

Keywords

Examples

			Table begins:
  1,    1,    1,    1,    1,    1, ...
  1,    1,    1,    1,    1,    1, ...
  1,    3,    3,    3,    3,    3, ...
  1,   16,   19,   22,   25,   28, ...
  1,  125,  185,  253,  329,  413, ...
  1, 1296, 2541, 4256, 6471, 9216, ...
		

Crossrefs

Main diagonal gives A306578.

Programs

  • Maple
    A:= proc(n,k) option remember; if n<=0 or k=0 then 1 else A(n-1,k)(((x+1)^k-1)/k) fi; unapply(convert(series(exp(x*%), x,n+1), polynom), x) end: T:= (n,k)-> coeff(A(n,k)(x), x,n)*n!: seq(seq(T(n,d-n), n=0..d), d=0..11);
  • Mathematica
    a[n_, k_][x_] := Module[{f}, f = If[n <= 0 || k == 0, 1, a[n-1, k][((#+1)^k-1)/k]]&; Normal[Series[Exp[y*f[y]], {y, 0, n+1}]] /. y -> x]; t[n_, k_] := Coefficient[a[n, k][x], x, n]*n!; Table[t[n, d-n], {d, 0, 11}, {n, 0, d}] // Flatten (* Jean-François Alcover, Feb 12 2014, translated from Maple *)

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
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