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!)
A177284 Number of permutations of 2 copies of 1..n with all adjacent differences <= 3 in absolute value. 1
1, 1, 6, 90, 2520, 41580, 516180, 6068622, 76331906, 958679970, 11679900408, 138047313960, 1610654864328, 18649754961744, 214256589488616, 2439692058769566, 27562317214408488, 309367132582535226, 3453299423388485028, 38354816922190327314, 424048220090513056908 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
a(n) = (2n)!/2^n for n<=4.
LINKS
CROSSREFS
Sequence in context: A177592 A177593 A132467 * A266735 A177564 A177565
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 06 2010
EXTENSIONS
a(0), a(13) from Alois P. Heinz, Jan 14 2016
Terms a(14) and beyond from Andrew Howroyd, May 14 2020
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 04:26 EDT 2024. Contains 370952 sequences. (Running on oeis4.)