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 A250387 T(n,k)=Number of length n+3 0..k arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms 13
 6, 42, 6, 156, 78, 6, 420, 432, 146, 6, 930, 1560, 1208, 274, 6, 1806, 4350, 5848, 3384, 514, 6, 3192, 10206, 20518, 21950, 9480, 966, 6, 5256, 21168, 58114, 96866, 82398, 26578, 1816, 6, 8190, 40032, 141344, 331128, 457366, 309452, 74528, 3414, 6, 12210 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Table starts .6....42.....156......420........930........1806........3192.........5256 .6....78.....432.....1560.......4350.......10206.......21168........40032 .6...146....1208.....5848......20518.......58114......141344.......306816 .6...274....3384....21950......96866......331128......944272......2352468 .6...514....9480....82398.....457366.....1886948.....6308960.....18038628 .6...966...26578...309452....2160160....10755158....42158796....138336744 .6..1816...74528..1162292...10203222....61304844...281731072...1060924200 .6..3414..208998..4365720...48194820...349446100..1882722300...8136444312 .6..6418..586102.16398414..227649458..1991900312.12581692558..62400176438 .6.12066.1643650.61595866.1075313612.11354195442.84080003928.478561255176 LINKS R. H. Hardin, Table of n, a(n) for n = 1..9999 FORMULA Empirical for column k, apparently recurrence of order 7*k-4: k=1: a(n) = a(n-1) k=2: a(n) = a(n-1) +2*a(n-2) -a(n-3) +3*a(n-4) -a(n-5) -7*a(n-6) +a(n-7) +a(n-10) k=3: [order 17] k=4: [order 24] k=5: [order 31] k=6: [order 38] k=7: [order 45] Empirical for row n, apparently polynomial of degree n+3: n=1: a(n) = n^4 + 2*n^3 + 2*n^2 + n n=2: a(n) = n^5 + (3/2)*n^4 + 2*n^3 + (3/2)*n^2 n=3: a(n) = n^6 + (16/15)*n^5 + (13/6)*n^4 + (5/3)*n^3 - (1/6)*n^2 + (4/15)*n n=4: [polynomial of degree 7] n=5: [polynomial of degree 8] n=6: [polynomial of degree 9] n=7: [polynomial of degree 10] EXAMPLE Some solutions for n=4 k=4 ..3....4....1....4....0....4....2....1....1....1....0....0....1....3....4....0 ..2....2....2....2....1....0....3....2....4....3....1....0....1....0....0....3 ..3....3....0....4....2....2....4....3....3....2....3....3....0....3....4....0 ..1....1....0....2....3....1....0....0....2....4....2....2....0....0....0....2 ..3....0....4....3....4....4....4....1....4....1....3....1....1....4....2....1 ..0....4....4....2....4....0....1....0....4....4....0....3....2....0....3....4 ..4....2....2....3....2....3....0....2....3....0....0....4....2....1....0....1 CROSSREFS Row 1 is A082986 Sequence in context: A181041 A109856 A249135 * A306429 A117693 A153243 Adjacent sequences:  A250384 A250385 A250386 * A250388 A250389 A250390 KEYWORD nonn,tabl AUTHOR R. H. Hardin, Nov 20 2014 STATUS approved

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Last modified August 5 22:11 EDT 2020. Contains 336214 sequences. (Running on oeis4.)