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 A183730 1/16 the number of (n+1) X 2 0..7 arrays with every 2 X 2 subblock strictly increasing clockwise or counterclockwise with one decrease, and at least two adjacent blocks having the same increasing direction. 1
 0, 21, 563, 9403, 135578, 1814815, 23204876, 287769879, 3491293862, 41667398364, 490998416023, 5727556631915, 66266101711488, 761498455531330, 8701271226331052, 98948856313647335, 1120614615517688964 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 1 of A183738. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n)=18*a(n-1)-46*a(n-2)-342*a(n-3)-33*a(n-4)+435*a(n-5)-157*a(n-6)-37*a(n-7)+21*a(n-8)-2*a(n-9). EXAMPLE Some solutions with the first block increasing clockwise for 3 X 2: ..4..5....6..0....1..2....1..2....2..4....4..5....7..0....2..3....0..2....0..2 ..2..6....5..1....7..4....0..3....0..5....1..6....6..1....1..4....7..3....6..3 ..1..7....4..2....6..5....7..4....7..6....0..7....4..3....0..7....6..4....5..4 ... ...R.......R.......R.......R.......R.......R.......R.......R.......R.......R... ...R.......R.......R.......R.......R.......R.......R.......R.......R.......R... CROSSREFS Sequence in context: A297635 A292062 A194022 * A199254 A199199 A089457 Adjacent sequences:  A183727 A183728 A183729 * A183731 A183732 A183733 KEYWORD nonn AUTHOR R. H. Hardin, Jan 06 2011 STATUS approved

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Last modified September 21 19:59 EDT 2019. Contains 327282 sequences. (Running on oeis4.)