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!)
A177559 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, down. 0
1, 6, 90, 2448, 105218, 6572088, 562874958, 63344668632, 9067009872984, 1608913338743280, 346665863545391736, 89160540714537206616, 26982910637581823115028, 9492077262717161359915632 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..14.

CROSSREFS

Sequence in context: A177580 A177587 A177585 * A177581 A177566 A177586

Adjacent sequences:  A177556 A177557 A177558 * A177560 A177561 A177562

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 10 2010

EXTENSIONS

a(11)-a(14) from Alois P. Heinz, Nov 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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 28 01:29 EDT 2021. Contains 348305 sequences. (Running on oeis4.)