|
|
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
|
|
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
|
|
|
KEYWORD
|
sign,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|