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!)
A094729 Number of connected ordered 2-element multiantichains on a labeled n-set. 10
0, 1, 1, 7, 37, 151, 541, 1807, 5797, 18151, 55981, 171007, 519157, 1569751, 4733821, 14250607, 42850117, 128746951, 386634061, 1160688607, 3483638677, 10454061751, 31368476701, 94118013007, 282379204837, 847187946151, 2541664501741, 7625194831807 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
E.g.f.: exp(3*x) - 3*exp(2*x) + 4*exp(x) - 2.
From Colin Barker, Jul 07 2013: (Start)
a(n) = 4-3*2^n+3^n for n>0.
a(n) = 6*a(n-1)-11*a(n-2)+6*a(n-3) for n>3.
G.f.: x*(1 - 5*x + 12*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)).
(End)
MATHEMATICA
With[{nmax = 50}, CoefficientList[Series[Exp[3*x] - 3*Exp[2*x] + 4*Exp[x] - 2, {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, Oct 06 2017 *)
LinearRecurrence[{6, -11, 6}, {0, 1, 1, 7}, 30] (* Harvey P. Dale, Aug 07 2023 *)
PROG
(PARI) x='x+O('x^50); concat([0], Vec(serlaplace(exp(3*x)-3*exp(2*x) +4*exp(x)-2))) \\ G. C. Greubel, Oct 06 2017
(PARI) concat(0, Vec(x*(1 - 5*x + 12*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)) + O(x^30))) \\ Colin Barker, Oct 13 2017
CROSSREFS
Sequence in context: A012885 A162541 A196574 * A202659 A202119 A201083
KEYWORD
nonn,easy
AUTHOR
Goran Kilibarda, Vladeta Jovovic, May 24 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 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)