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 A245876 Number of length 7+2 0..n arrays with some pair in every consecutive three terms totalling exactly n. 1
 110, 2967, 12100, 40901, 97602, 214315, 404264, 727017, 1200310, 1920671, 2909100, 4309357, 6143690, 8614131, 11741392, 15797585, 20798334, 27098407, 34704020, 44065941, 55175890, 68594747, 84293880, 102959161, 124534982, 149847855 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + 3*a(n-2) - 8*a(n-3) - 2*a(n-4) + 12*a(n-5) - 2*a(n-6) - 8*a(n-7) + 3*a(n-8) + 2*a(n-9) - a(n-10). Conjectures from Colin Barker, Nov 05 2018: (Start) G.f.: x*(110 + 2747*x + 5836*x^2 + 8680*x^3 + 3456*x^4 - 2178*x^5 - 1148*x^6 - 224*x^7 + 2*x^8 - x^9) / ((1 - x)^6*(1 + x)^4). a(n) = 1 + 37*n + 43*n^2 + 126*n^3 + 89*n^4 + 9*n^5 for n even. a(n) = 7 - 76*n - 41*n^2 + 122*n^3 + 89*n^4 + 9*n^5 for n odd. (End) EXAMPLE Some solutions for n=5: ..2....4....0....4....0....0....2....3....4....2....3....3....4....1....1....5 ..2....1....5....3....2....3....4....0....1....0....3....5....3....3....0....0 ..3....2....1....2....3....2....1....5....5....5....2....0....2....2....4....5 ..2....3....4....3....0....5....3....0....0....3....3....1....5....5....5....2 ..3....3....1....2....5....3....4....0....4....2....0....4....3....3....0....3 ..3....2....2....4....3....2....1....5....1....0....5....2....2....2....5....5 ..2....2....3....1....2....2....4....3....4....3....2....1....2....3....4....2 ..3....3....2....0....1....3....2....2....2....2....0....3....3....2....1....0 ..1....2....4....4....3....2....1....0....3....4....3....2....5....4....5....5 CROSSREFS Row 7 of A245869. Sequence in context: A008450 A163729 A251020 * A185536 A201833 A035836 Adjacent sequences: A245873 A245874 A245875 * A245877 A245878 A245879 KEYWORD nonn AUTHOR R. H. Hardin, Aug 04 2014 STATUS approved

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Last modified December 10 17:36 EST 2023. Contains 367713 sequences. (Running on oeis4.)