login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons 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 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A249962 Number of length 2+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, 505, 5300, 31180, 129095, 422065, 1164800, 2830080, 6226935, 12655665, 24104740, 43494620, 74973535, 124270265, 199108960, 309691040, 469249215, 694678665, 1007250420, 1433411980, 2005680215, 2763631585, 3754994720 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A249960.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = n^7 + (13/6)*n^6 + (13/3)*n^5 + (65/12)*n^4 + (3/2)*n^3 - (1/12)*n^2 + (2/3)*n.

Conjectures from Colin Barker, Aug 21 2017: (Start)

G.f.: 5*x*(1 + x)*(3 + 74*x + 262*x^2 + 154*x^3 + 11*x^4) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

EXAMPLE

Some solutions for n=5:

..1....5....2....1....3....0....5....2....3....2....3....3....1....3....1....2

..4....1....1....2....4....2....0....3....0....2....0....0....5....0....1....0

..5....5....0....4....0....3....5....0....5....2....5....3....4....1....2....0

..3....5....3....1....4....5....1....1....5....0....4....1....5....3....3....4

..0....3....4....3....5....0....0....2....1....0....0....4....5....3....3....4

..2....5....2....5....0....5....3....0....5....5....2....3....2....3....2....3

..0....5....2....1....2....5....1....4....2....3....5....3....3....0....1....3

CROSSREFS

Sequence in context: A208099 A219057 A203525 * A004703 A218188 A218365

Adjacent sequences:  A249959 A249960 A249961 * A249963 A249964 A249965

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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 22:32 EST 2021. Contains 349468 sequences. (Running on oeis4.)