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A053557 Numerator of Sum_{k=0..n} (-1)^k/k!. 13
1, 0, 1, 1, 3, 11, 53, 103, 2119, 16687, 16481, 1468457, 16019531, 63633137, 2467007773, 34361893981, 15549624751, 8178130767479, 138547156531409, 92079694567171, 4282366656425369, 72289643288657479, 6563440628747948887, 39299278806015611311 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

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

Also denominators 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, Continued Fraction Constants

Eric Weisstein's World of Mathematics, Generalized Continued Fraction

Eric Weisstein's World of Mathematics, Subfactorial

FORMULA

Let -e^(-x)/(x-1)= Sum_{n >= 0} a_n/b_n *x^n . Then sequence a_n is A053557. - 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

Numerator[ CoefficientList[ Series[E^-x/(1-x), {x, 0, 23}], x]] (* Jean-François Alcover, Nov 18 2011 *)

Table[Numerator[Sum[(-1)^k/k!, {k, 0, n}]], {n, 0, 30}] (* Harvey P. Dale, Dec 02 2011 *)

Numerator[RecurrenceTable[{a(n) = a(n - 1) + (a(n - 2))/(n - 2), a(1) = 0, a(2) = 1}, a, {n, 2, 30}]] (* Terry D. Grant, May 07 2017 *)

PROG

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

CROSSREFS

Cf. A000166/A000142, A053556 (denominators), A053518-A053520. See also A103816.

a(n) = (N(n, n) of A103361), A053557/A053556 = A000166/n! = (N(n, n) of A103361)/(D(n, n) of A103360), Cf. A053518-A053520.

Sequence in context: A321585 A107958 A253972 * A039302 A074512 A005502

Adjacent sequences:  A053554 A053555 A053556 * A053558 A053559 A053560

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 19 20:18 EST 2019. Contains 319310 sequences. (Running on oeis4.)