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 A270058 T(n,k)=Number of nXk 0..4 arrays with some element plus some horizontally or vertically adjacent neighbor totalling four exactly once. 8
 0, 5, 5, 40, 240, 40, 240, 5400, 5400, 240, 1280, 99840, 385200, 99840, 1280, 6400, 1683240, 22911300, 22911300, 1683240, 6400, 30720, 26891280, 1248460920, 4410058320, 1248460920, 26891280, 30720, 143360, 414705720, 64599504300 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Table starts ......0...........5...............40...................240 ......5.........240.............5400.................99840 .....40........5400...........385200..............22911300 ....240.......99840.........22911300............4410058320 ...1280.....1683240.......1248460920..........779206497960 ...6400....26891280......64599504300.......130850370606120 ..30720...414705720....3230189811360.....21244602958557060 .143360..6237722400..157641639369300...3367363526042121600 .655360.92095515720.7554828673749960.524230216822482202860 LINKS R. H. Hardin, Table of n, a(n) for n = 1..180 FORMULA Empirical for column k: k=1: a(n) = 8*a(n-1) -16*a(n-2) k=2: a(n) = 26*a(n-1) -169*a(n-2) for n>3 k=3: a(n) = 90*a(n-1) -2257*a(n-2) +10440*a(n-3) -13456*a(n-4) for n>5 k=4: [order 6] for n>7 k=5: [order 14] for n>15 k=6: [order 26] for n>27 k=7: [order 64] for n>65 EXAMPLE Some solutions for n=2 k=4 ..4..3..1..0. .2..1..0..2. .3..3..4..3. .0..3..1..2. .0..3..4..3 ..3..3..0..0. .1..4..0..1. .2..1..2..4. .1..0..1..0. .0..4..2..3 CROSSREFS Column 1 is A269822. Sequence in context: A271083 A271277 A269829 * A270156 A270164 A270181 Adjacent sequences:  A270055 A270056 A270057 * A270059 A270060 A270061 KEYWORD nonn,tabl AUTHOR R. H. Hardin, Mar 09 2016 STATUS approved

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Last modified August 10 03:08 EDT 2020. Contains 336367 sequences. (Running on oeis4.)