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!)
A221685 Number of 0..n arrays of length 6 with each element differing from at least one neighbor by 1 or less, starting with 0. 1
32, 113, 241, 418, 636, 891, 1182, 1509, 1872, 2271, 2706, 3177, 3684, 4227, 4806, 5421, 6072, 6759, 7482, 8241, 9036, 9867, 10734, 11637, 12576, 13551, 14562, 15609, 16692, 17811, 18966, 20157, 21384, 22647, 23946, 25281, 26652, 28059, 29502, 30981 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 6 of A221683.

LINKS

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

FORMULA

Empirical: a(n) = 18*n^2 + 57*n - 99 for n>4.

Conjectures from Colin Barker, Aug 10 2018: (Start)

G.f.: x*(32 + 17*x - 2*x^2 + 2*x^3 - 8*x^4 - 4*x^5 - x^6) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>7.

(End)

EXAMPLE

Some solutions for n=6:

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

..1....0....0....1....1....0....1....0....1....0....0....0....1....0....1....0

..3....0....2....5....0....6....3....0....0....1....5....6....0....1....4....4

..4....0....1....5....3....5....4....1....5....5....4....6....0....3....4....5

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

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

CROSSREFS

Cf. A221683.

Sequence in context: A203728 A044283 A044664 * A203721 A231527 A298201

Adjacent sequences:  A221682 A221683 A221684 * A221686 A221687 A221688

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 22 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 26 09:52 EDT 2022. Contains 354879 sequences. (Running on oeis4.)