login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A317282 Number of permutations of [n] with exactly two increasing runs of even length. 2
5, 43, 258, 1853, 15634, 133697, 1207256, 11974457, 126980013, 1421291622, 16925790480, 213992804118, 2851968574855, 39996895523591, 589713707701692, 9114791365659163, 147335664946835342, 2486973983349027871, 43763134470537718258, 801419373432471123541 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..472

MAPLE

b:= proc(u, o, t) option remember; series(`if`(u+o=0, x^t,

add(b(u+j-1, o-j, irem(t+1, 2)), j=1..o)+

add(b(u-j, o+j-1, 0)*x^t, j=1..u)), x, 3)

end:

a:= n-> coeff(b(n, 0$2), x, 2):

seq(a(n), n=4..30);

CROSSREFS

Column k=2 of A097592.

Sequence in context: A173554 A126963 A221874 * A182191 A038140 A178826

Adjacent sequences: A317279 A317280 A317281 * A317283 A317284 A317285

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jul 25 2018

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 December 7 14:31 EST 2022. Contains 358656 sequences. (Running on oeis4.)