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!)
A123225 Triangle read by rows: T(n,d) = (n!/d!)*(n+1)*binomial(2n-d+1,n+1)/(n-d+1) (0 <= d <= n). 1
1, 3, 2, 20, 12, 3, 210, 120, 30, 4, 3024, 1680, 420, 60, 5, 55440, 30240, 7560, 1120, 105, 6, 1235520, 665280, 166320, 25200, 2520, 168, 7, 32432400, 17297280, 4324320, 665280, 69300, 5040, 252, 8, 980179200, 518918400, 129729600, 20180160, 2162160 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
E. Babson and E. Steingrimsson, Generalized permutation patterns and a classification of the Mahonian statistics, Séminaire Lotharingien de Combinatoire, Paper B44b, 2000 (see p. 8).
FORMULA
T(n,d) = (n!/d!)*Sum_{k=0..n} binomial(n-d+k,k) (0 <= d <= n).
T(n,d) = (n!/d!)*(n+1)*binomial(2n-d+1,n+1)/(n-d+1) (0 <= d <= n).
EXAMPLE
Triangle begins:
1;
3, 2;
20, 12, 3;
210, 120, 30, 4;
3024, 1680, 420, 60, 5;
MAPLE
T:=proc(n, d) if d<=n then n!*(n+1)*binomial(2*n-d+1, n+1)/d!/(n-d+1) else 0 fi end: for n from 0 to 9 do seq(T(n, d), d=0..n) od; # yields sequence in triangular form
MATHEMATICA
T[n_, d_, k_] = (n!/d!)*Binomial[n - d + k, k]; a = Table[Table[Sum[T[n, d, k], {k, 0, n}], {d, 0, n}], {n, 0, 10}]; Flatten[a]
PROG
(PARI) for(n=0, 12, for(k=0, n, print1((n!/k!)*(n+1)*binomial(2*n-k+1, n+1)/(n-k+1), ", "))) \\ G. C. Greubel, Oct 12 2018
(Magma) [[(Factorial(n)/Factorial(k))*(n+1)*Binomial(2*n-k+1, n+1)/(n - k +1): k in [0..n]]: n in [0..12]]; // G. C. Greubel, Oct 12 2018
(GAP) Flat(List([0..8], n->List([0..n], d->(Factorial(n)/Factorial(d))*(n+1)*Binomial(2*n-d+1, n+1)/(n-d+1)))); # Muniru A Asiru, Oct 12 2018
CROSSREFS
Cf. A008302.
Sequence in context: A154261 A098655 A065038 * A009028 A009022 A009033
KEYWORD
nonn,tabl
AUTHOR
Roger L. Bagula, Oct 05 2006
EXTENSIONS
Edited by N. J. A. Sloane, Oct 08 2006
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 July 18 21:02 EDT 2024. Contains 374388 sequences. (Running on oeis4.)