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!)
A098276 Difference between the number of even reduced Latin rectangles of size 3 X n and the number of odd ones. 1
1, 0, 2, 0, 72, -320, 3600, -32256, 344960, -3926016, 48625920, -648243200, 9270125568, -141579509760, 2300668418048, -39642283376640, 722055883161600, -13863472939925504, 279868860012625920 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
E.g.f.: x + [(1-x)^2/(1+x)+x/(1+x)^2] * exp(2x). - corrected by Vaclav Kotesovec, Sep 29 2013
a(n) ~ n! * (-1)^(n+1) * n * exp(-2). - Vaclav Kotesovec, Sep 29 2013
MATHEMATICA
Rest[CoefficientList[Series[x + ((1-x)^2/(1+x)+x/(1+x)^2)*E^(2*x), {x, 0, 20}], x]* Range[0, 20]!] (* Vaclav Kotesovec, Sep 29 2013 *)
PROG
(PARI) a(n)=polcoeff(serlaplace(exp(2*x)*((1-x)^2/(1+x)+x/(1+x)^2)), n)
(PARI) a(n)=(-1)^(n-1)*(n-2)*n!/2*polcoeff(Ser(exp(2*(atanh(x)-x))), n)
CROSSREFS
Cf. A000186.
Sequence in context: A264437 A306061 A195209 * A335692 A215880 A030129
KEYWORD
sign,easy
AUTHOR
Ralf Stephan, Sep 06 2004
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 02:44 EDT 2024. Contains 370952 sequences. (Running on oeis4.)