login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A090588 Number of labeled idempotent groupoids. 5
1, 1, 4, 729, 16777216, 95367431640625, 221073919720733357899776, 311973482284542371301330321821976049, 374144419156711147060143317175368453031918731001856, 507528786056415600719754159741696356908742250191663887263627442114881 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

Index entries for sequences related to groupoids

FORMULA

a(n) = n^(n^2 - n).

MAPLE

a:=n->mul(mul(sum(1, j=0..n), k=0..n), m=1..n): seq(a(n), n=-1..7); # Zerinvary Lajos, Dec 31 2008

MATHEMATICA

Join[{1}, Table[n^(n^2-n), {n, 10}]] (* Harvey P. Dale, Sep 16 2013 *)

PROG

(Ruby)

def a(n)

ids =* (0..n-1)

return (ids.product(ids)).reduce(1){ |accum, x|  (x[0] == x[1]) ? accum :  accum*ids.length}

end

# Chad Brewbaker, Nov 03 2013

(PARI) a(n) = n^(n^2-n); \\ Joerg Arndt, Nov 04 2013

(MAGMA) [n^(n^2 - n): n in [0..10]]; // Vincenzo Librandi, Aug 08 2015

CROSSREFS

Cf. A002489, A030247, A076113.

Sequence in context: A219012 A059754 A134579 * A053986 A222961 A160737

Adjacent sequences:  A090585 A090586 A090587 * A090589 A090590 A090591

KEYWORD

nonn

AUTHOR

Christian G. Bower, Dec 03 2003

EXTENSIONS

One additional term from Harvey P. Dale, Sep 16 2013

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 August 12 11:44 EDT 2020. Contains 336439 sequences. (Running on oeis4.)