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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A226288 T(n,k) = [n/2]!*[(n+1)/2]!*C([n/2],k-1)*C([(n+1)/2],k-1). 7
 1, 0, 1, 0, 1, 2, 0, 0, 4, 4, 0, 0, 0, 16, 12, 0, 0, 0, 4, 72, 36, 0, 0, 0, 0, 36, 324, 144, 0, 0, 0, 0, 0, 324, 1728, 576, 0, 0, 0, 0, 0, 36, 2592, 9216, 2880, 0, 0, 0, 0, 0, 0, 576, 20736, 57600, 14400, 0, 0, 0, 0, 0, 0, 0, 9216, 172800, 360000, 86400, 0, 0, 0, 0, 0, 0, 0, 576 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS T(n,k)=Number of permutations of n elements with 2k-2 odd displacements Table starts: .........1...........0............0............0............0............0 .........1...........1............0............0............0............0 .........2...........4............0............0............0............0 .........4..........16............4............0............0............0 ........12..........72...........36............0............0............0 ........36.........324..........324...........36............0............0 .......144........1728.........2592..........576............0............0 .......576........9216........20736.........9216..........576............0 ......2880.......57600.......172800.......115200........14400............0 .....14400......360000......1440000......1440000.......360000........14400 .....86400.....2592000.....12960000.....17280000......6480000.......518400 ....518400....18662400....116640000....207360000....116640000.....18662400 ...3628800...152409600...1143072000...2540160000...1905120000....457228800 ..25401600..1244678400..11202105600..31116960000..31116960000..11202105600 .203212800.11379916800.119489126400.398297088000.497871360000.238978252800 LINKS R. H. Hardin, Table of n, a(n) for n = 1..10000 CROSSREFS Column 1 is A010551. Columns 2-7 are: A226282-A226287. Cf. A145891 (another version as irregular triangle) Sequence in context: A147592 A108885 A072740 * A185146 A080964 A134014 Adjacent sequences:  A226285 A226286 A226287 * A226289 A226290 A226291 KEYWORD nonn,tabl AUTHOR R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 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.

Last modified May 25 10:57 EDT 2020. Contains 334592 sequences. (Running on oeis4.)