login
A289711
Triangle T(n,p) read by rows: the order of the semigroup of orientation-preserving partial transformations of n elements with height p.
2
1, 1, 1, 1, 6, 2, 1, 21, 36, 3, 1, 60, 288, 96, 4, 1, 155, 1600, 1200, 200, 5, 1, 378, 7200, 9600, 3600, 360, 6, 1, 889, 28224, 58800, 39200, 8820, 588, 7, 1, 2040, 100352, 301056, 313600, 125440, 18816, 896, 8, 1, 4599, 331776, 1354752, 2032128, 1270080, 338688
OFFSET
0,5
EXAMPLE
1 ;
1 1 ;
1 6 2 ;
1 21 36 3 ;
1 60 288 96 4;
1 155 1600 1200 200 5;
1 378 7200 9600 3600 360 6;
1 889 28224 58800 39200 8820 588 7;
1 2040 100352 301056 313600 125440 18816 896 8 ;
1 4599 331776 1354752 2032128 1270080 338688 36288 1296 9;
1 10230 1036800 5529600 11289600 10160640 4233600 806400 64800 1800 10 ;
MAPLE
A289711 := proc(n, p)
if p = 0 then
1;
elif p = 1 then
n*(2^n-1) ;
else
p*2^(n-p)*binomial(n, p)^2 ;
end if ;
end proc:
CROSSREFS
Cf. A066524 (column p=1), A289713 (row sums).
Sequence in context: A002247 A124913 A181415 * A101818 A138186 A110321
KEYWORD
tabl,nonn,easy
AUTHOR
R. J. Mathar, Sep 02 2017
STATUS
approved