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A223425 5 X 5 X 5 triangular graph without horizontal edges coloring a rectangular array: number of n X 1 0..14 arrays where 0..14 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 3,6 3,7 4,7 4,8 5,8 5,9 6,10 6,11 7,11 7,12 8,12 8,13 9,13 9,14 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
15, 40, 120, 356, 1088, 3276, 10052, 30380, 93296, 282240, 866908, 2623264, 8057756, 24384556, 74901596, 226673608, 696270792, 2107127204, 6472442928, 19587617308, 60167110388, 182084416108, 559307110768, 1692637810416, 5199260845212 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A223432.

LINKS

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

FORMULA

Empirical: a(n) = 14*a(n-2) - 49*a(n-4) + 49*a(n-6) for n>7.

Empirical g.f.: x*(15 + 40*x - 90*x^2 - 204*x^3 + 143*x^4 + 252*x^5 - 35*x^6) / ((1 - 7*x^2 + 7*x^3)*(1 - 7*x^2 - 7*x^3)). - Colin Barker, Aug 20 2018

EXAMPLE

Some solutions for n=3:

..5....1....8....3....2....2...10....6....4....7....2....7....0....2....4....8

..8....4....5....7....5....4....6....3....8....3....0....3....2....4....2....5

.13....2....8...12....2....2....3....6....5....1....2....7....4....8....4....9

CROSSREFS

Cf. A223432.

Sequence in context: A067724 A005337 A160891 * A175926 A038991 A068020

Adjacent sequences:  A223422 A223423 A223424 * A223426 A223427 A223428

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 20 2013

STATUS

approved

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Last modified April 25 13:31 EDT 2019. Contains 322461 sequences. (Running on oeis4.)