A198247 - OEIS

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

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 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A198247

Number of 2n X 4 0..4 arrays with values 0..4 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors.

1, 5, 40, 485, 6528, 90641, 1268648, 17794141, 249720000, 3505037833, 49198133832, 690571872597, 9693269289152, 136060470673025, 1909825721373608, 26807451423465421, 376285360845321600, 5281765543824353657

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Column 2 of A198253.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 20*a(n-1) -85*a(n-2) -16*a(n-3) +493*a(n-4) -124*a(n-5) -919*a(n-6) +120*a(n-7) +512*a(n-8).

Empirical g.f.: x*(1 - 15*x + 25*x^2 + 126*x^3 - 185*x^4 - 395*x^5 + 287*x^6 + 444*x^7) / ((1 - x)*(1 + x)*(1 - 4*x - x^2 + 8*x^3)*(1 - 16*x + 23*x^2 + 64*x^3)). - Colin Barker, May 14 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

CROSSREFS

Cf. A198253.

Sequence in context: A201366 A281160 A282476 * A088695 A365779 A145166

Adjacent sequences: A198244 A198245 A198246 * A198248 A198249 A198250

KEYWORD

nonn

AUTHOR

R. H. Hardin Oct 22 2011

STATUS

approved