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A245953 Number of length 3+3 0..n arrays with some pair in every consecutive four terms totalling exactly n. 1
48, 545, 2304, 7769, 18384, 39721, 73728, 130193, 211440, 332561, 496128, 723625, 1017744, 1407449, 1895424, 2519201, 3281328, 4228993, 5364480, 6745721, 8374608, 10320905, 12585984, 15252529, 18321264, 21888881, 25955328, 30632393, 35919120 (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) = 3*a(n-1) - 8*a(n-3) + 6*a(n-4) + 6*a(n-5) - 8*a(n-6) + 3*a(n-8) - a(n-9).

Conjectures from Colin Barker, Nov 05 2018: (Start)

G.f.: x*(48 + 401*x + 669*x^2 + 1241*x^3 - 851*x^4 - 557*x^5 + 7*x^6 + 3*x^7 - x^8) / ((1 - x)^6*(1 + x)^3).

a(n) = 1 + 26*n - 17*n^2 + 24*n^3 + 21*n^4 + n^5 for n even.

a(n) = 39 - n - 36*n^2 + 24*n^3 + 21*n^4 + n^5 for n odd.

(End)

EXAMPLE

Some solutions for n=8:

..3....4....6....3....2....2....5....0....0....3....1....3....2....6....5....1

..1....3....7....8....8....0....1....1....6....2....8....8....6....3....4....5

..2....4....2....5....7....8....5....4....8....4....0....4....1....6....2....3

..6....5....8....3....1....4....7....7....3....5....6....5....5....5....6....8

..3....1....6....1....8....6....1....6....5....4....6....4....2....2....6....0

..2....7....2....2....1....0....4....2....2....1....2....8....6....1....0....8

CROSSREFS

Row 3 of A245950.

Sequence in context: A189346 A334713 A266210 * A192832 A042949 A190601

Adjacent sequences:  A245950 A245951 A245952 * A245954 A245955 A245956

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 08 2014

STATUS

approved

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Last modified May 7 20:32 EDT 2021. Contains 343652 sequences. (Running on oeis4.)