login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A088679 a(n) = a(n-1)^2 * n / (n-1), n>1, a(0) = 0, a(1) = 1. 2
0, 1, 2, 6, 48, 2880, 9953280, 115579079884800, 15266884236590834264309760000, 262212473580148912869121218589990322256745385164800000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Unreduced numerators of: f(1) = 1, f(n) = f(n-1) + f(n-1)/(n-1). - Daniel Suteu, Jul 29 2016

LINKS

Table of n, a(n) for n=0..9.

FORMULA

a(n) is asymptotic to c^(2^n)*(1-1/n+2/n^2-6/n^3+25/n^4-137/n^5+...) where c=1.28906475773... and coefficient of n^-k is (-1)^k*A084784(k).

a(0) = 0, a(1) = 1, a(n) = n * Product i=1..(n-1) a(i) for n > 1. - Gerald McGarvey, Jun 11 2004 Corrected by Jaroslav Krizek, Oct 16 2009

a(n)^2 = n * A052129(n). Michael Somos, May 13 2012

a(n+1)/A052129(n) = n+1. - Daniel Suteu, Jul 29 2016

EXAMPLE

x + 2*x^2 + 6*x^3 + 48*x^4 + 2880*x^5 + 9953280*x^6 + ...

MATHEMATICA

Join[{0}, RecurrenceTable[{a[1]==1, a[n]==a[n-1]^2 n/(n-1)}, a, {n, 10}]] (* Harvey P. Dale, Jan 16 2015 *)

PROG

(PARI) {a(n) = if( n<2, n>0, a(n-1)^2 * n / (n-1))}

CROSSREFS

Cf. A052129.

Sequence in context: A230053 A245283 A126023 * A161766 A074020 A080310

Adjacent sequences:  A088676 A088677 A088678 * A088680 A088681 A088682

KEYWORD

nonn

AUTHOR

Michael Somos, Oct 05 2003

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 December 13 23:26 EST 2018. Contains 318087 sequences. (Running on oeis4.)