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A246473 Number of length n+3 0..2 arrays with no pair in any consecutive four terms totalling exactly 2. 2
10, 14, 20, 28, 38, 52, 72, 100, 138, 190, 262, 362, 500, 690, 952, 1314, 1814, 2504, 3456, 4770, 6584, 9088, 12544, 17314, 23898, 32986, 45530, 62844, 86742, 119728, 165258, 228102, 314844, 434572, 599830, 827932, 1142776, 1577348, 2177178 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A246479.
LINKS
FORMULA
Empirical: a(n) = a(n-1) + a(n-4).
Empirical g.f.: 2*x*(5 + 2*x + 3*x^2 + 4*x^3) / (1 - x - x^4). - Colin Barker, Mar 19 2018
EXAMPLE
Some solutions for n=6:
..2....0....2....2....1....0....1....0....2....1....2....1....0....0....0....1
..2....0....2....2....0....0....2....0....2....0....1....2....0....1....0....2
..2....0....1....2....0....0....2....1....2....0....2....2....0....0....0....2
..2....0....2....2....0....1....2....0....1....0....2....2....1....0....0....2
..2....0....2....2....0....0....2....0....2....0....2....1....0....0....0....2
..2....0....2....2....0....0....1....0....2....1....2....2....0....0....0....2
..2....0....2....2....0....0....2....0....2....0....2....2....0....0....0....2
..1....0....2....2....1....0....2....0....2....0....1....2....1....1....0....2
..2....0....2....1....0....0....2....0....1....0....2....1....0....0....1....2
CROSSREFS
Cf. A246479.
Sequence in context: A245729 A031274 A272375 * A063920 A269703 A057487
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 27 2014
STATUS
approved

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Last modified April 24 04:14 EDT 2024. Contains 371918 sequences. (Running on oeis4.)