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A053556 Denominator of Sum_{k=0..n} (-1)^k/k!. 14
1, 1, 2, 3, 8, 30, 144, 280, 5760, 45360, 44800, 3991680, 43545600, 172972800, 6706022400, 93405312000, 42268262400, 22230464256000, 376610217984000, 250298560512000, 11640679464960000, 196503623737344000, 17841281393295360000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Denominator of probability of a derangement of n things (A000166(n)/n!).

Also numerators of successive convergents to e using continued fraction 2+1/(1+1/(2+2/(3+3/(4+4/(5+5/(6+6/(7+7/8+...))))))).

REFERENCES

L. Lorentzen and H. Waadeland, Continued Fractions with Applications, North-Holland 1992, p. 562.

E. Maor, e: The Story of a Number, Princeton Univ. Press 1994, pp. 151 and 157.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..450 (terms 0..100 from T. D. Noe)

Leonhardo Eulero, Introductio in analysin infinitorum. Tomus primus, Lausanne, 1748.

L. Euler, Introduction à l'analyse infinitésimale, Tome premier, Tome second, trad. du latin en français par J. B. Labey, Paris, 1796-1797.

Eric Weisstein's World of Mathematics, Subfactorial

FORMULA

Let -e^(-x)/(x-1)= Sum(n, 0, infty)a_n/b_n *x^n . Then sequence b_n is A053556 - Aleksandar Petojevic (apetoje(AT)ptt.yu), Apr 14 2004

EXAMPLE

1, 0, 1/2, 1/3, 3/8, 11/30, 53/144, 103/280, 2119/5760, ...

MATHEMATICA

Table[ Denominator[ Sum[ -(-1)^k/k!, {k, 0, n}]], {n, 0, 20}] (* Robert G. Wilson v, Oct 13 2005 *)

Table[ Denominator[1 - Subfactorial[n]/n!], {n, 0, 22}] (* Jean-François Alcover, Feb 11 2014 *)

Denominator[Accumulate[Table[(-1)^k/k!, {k, 0, 30}]]] (* Harvey P. Dale, Aug 22 2016 *)

PROG

(PARI) for(n=0, 50, print1(denominator(sum(k=0, n, (-1)^k/k!)), ", ")) \\ G. C. Greubel, Nov 05 2017

CROSSREFS

Cf. A053557 (numerators), A053518-A053520. See also A103816.

a(n) = (D(n, n) of A103360), A053557/A053556 = A000166/n! = (N(n, n) of A103361)/(D(n, n) of A103360).

Sequence in context: A012886 A078918 A054104 * A301737 A001048 A141520

Adjacent sequences:  A053553 A053554 A053555 * A053557 A053558 A053559

KEYWORD

nonn,frac,nice,easy

AUTHOR

N. J. A. Sloane, Jan 17 2000

EXTENSIONS

More terms from Vladeta Jovovic, Mar 31 2000

STATUS

approved

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Last modified January 22 09:52 EST 2019. Contains 319363 sequences. (Running on oeis4.)