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!)
A208378 Number of n X 7 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 1 0 1 vertically. 1
42, 1764, 6216, 13860, 25200, 40740, 60984, 86436, 117600, 154980, 199080, 250404, 309456, 376740, 452760, 538020, 633024, 738276, 854280, 981540, 1120560, 1271844, 1435896, 1613220, 1804320, 2009700, 2229864, 2465316, 2716560, 2984100, 3268440 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 7 of A208379.
LINKS
FORMULA
Empirical: a(n) = 84*n^3 + 840*n^2 - 1344*n + 420 for n>1.
Conjectures from Colin Barker, Jul 02 2018: (Start)
G.f.: 42*x*(1 + 38*x - 14*x^2 - 14*x^3 + x^4) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>5.
(End)
EXAMPLE
Some solutions for n=4:
..1..1..0..1..0..0..1....0..1..0..1..0..0..1....1..0..1..1..0..0..1
..1..1..0..0..1..1..0....0..1..1..0..1..1..0....1..1..0..0..1..1..0
..1..1..0..0..1..1..0....0..1..1..0..0..1..0....0..1..0..0..1..1..0
..0..1..0..0..1..0..0....0..0..1..0..0..1..0....0..1..0..0..1..0..0
CROSSREFS
Cf. A208379.
Sequence in context: A207588 A207844 A206986 * A208068 A207933 A207850
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 25 2012
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 April 13 22:20 EDT 2024. Contains 371646 sequences. (Running on oeis4.)