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!)
A249961 Number of length 1+5 0..n arrays with no six consecutive terms having the maximum of any two terms equal to the minimum of the remaining four terms. 1
15, 285, 2010, 8790, 28785, 77595, 181860, 383580, 745155, 1355145, 2334750, 3845010, 6094725, 9349095, 13939080, 20271480, 28839735, 40235445, 55160610, 74440590, 99037785, 130066035, 168805740, 216719700, 275469675, 346933665 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Row 1 of A249960.
LINKS
FORMULA
Empirical: a(n) = n^6 + 3*n^5 + 5*n^4 + 5*n^3 + (3/2)*n^2 - (1/2)*n.
Conjectures from Colin Barker, Aug 21 2017: (Start)
G.f.: 15*x*(1 + x)^2*(1 + 10*x + x^2) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)
EXAMPLE
Some solutions for n=6:
..1....0....3....4....2....2....3....4....3....1....0....4....4....1....0....0
..3....4....1....2....4....5....1....2....3....3....1....2....1....6....0....3
..3....5....3....5....3....5....3....0....6....5....0....4....6....4....3....4
..5....3....1....3....0....6....2....3....6....2....2....1....5....1....6....1
..0....2....3....5....4....5....3....1....0....5....4....1....1....3....1....6
..4....0....2....1....4....3....3....6....1....0....3....2....2....5....3....4
CROSSREFS
Sequence in context: A095654 A279167 A249960 * A177074 A069405 A125055
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 09 2014
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 28 08:22 EDT 2024. Contains 371236 sequences. (Running on oeis4.)