login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A174481 a(n) = coefficient of x^n/(n-1)! in the (n-1)-th iteration of x*exp(x) for n>=1. 5
1, 1, 6, 102, 3400, 187455, 15441636, 1776667928, 272145104736, 53540399628405, 13156413372354340, 3949011172491569316, 1421739781364268435576, 604701975767931070422939, 299969585267917154906689660 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

The initial n-th iterations of x*exp(x) begin:

n=0: (1)*x;

n=1: x + (1)*x^2 + x^3/2! + x^4/3! + x^5/4! + x^6/5! +...

n=2: x + 2*x^2 +(6)*x^3/2! + 23*x^4/3! + 104*x^5/4! + 537*x^6/5! +...

n=3: x + 3*x^2 +15*x^3/2! +(102)*x^4/3! +861*x^5/4! +8598*x^6/5! +...

n=4: x + 4*x^2 +28*x^3/2! +274*x^4/3! +(3400)*x^5/4! +50734*x^6/5! +...

n=5: x + 5*x^2 +45*x^3/2! +575*x^4/3! +9425*x^5/4! +(187455)*x^6/5!+...

n=6: x + 6*x^2 +66*x^3/2! +1041*x^4/3! +21216*x^5/4!+527631*x^6/5! + (15441636)*x^7/6! +...

This sequence starts with the above coefficients in parathesis.

PROG

(PARI) {a(n)=local(E=x*exp(x+x*O(x^n)), F=x); for(i=1, n-1, F=subst(F, x, E)); (n-1)!*polcoeff(F, n)}

CROSSREFS

Cf. A174480, A174482, A174483, A174484.

Sequence in context: A277662 A022025 A302911 * A306205 A106303 A157518

Adjacent sequences:  A174478 A174479 A174480 * A174482 A174483 A174484

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 09 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 23 12:51 EST 2022. Contains 350511 sequences. (Running on oeis4.)