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A245872 Number of length 3+2 0..n arrays with some pair in every consecutive three terms totalling exactly n. 1
16, 103, 256, 549, 960, 1579, 2368, 3433, 4720, 6351, 8256, 10573, 13216, 16339, 19840, 23889, 28368, 33463, 39040, 45301, 52096, 59643, 67776, 76729, 86320, 96799, 107968, 120093, 132960, 146851, 161536, 177313, 193936, 211719, 230400, 250309 (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) + a(n-2) - 4*a(n-3) + a(n-4) + 2*a(n-5) - a(n-6).

Conjectures from Colin Barker, Nov 04 2018: (Start)

G.f.: x*(16 + 71*x + 34*x^2 - 2*x^3 + 2*x^4 - x^5) / ((1 - x)^4*(1 + x)^2).

a(n) = 1 + 5*n + 13*n^2 + 5*n^3 for n even.

a(n) = -5 + 3*n + 13*n^2 + 5*n^3 for n odd.

(End)

EXAMPLE

Some solutions for n=10:

  7   7   7   5   1   9   3   6   4   9  10  10   5   2   9   0

  3   4   3   5   1   9  10   4   2   1   8   0   7   4   5   6

  5   6   5   4   9   1   7  10   8   4   2  10   5   6   5   4

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

  4   4   3   6   5   9  10   6   2   4   6   6   8   1   3   6

CROSSREFS

Row 3 of A245869.

Sequence in context: A264281 A240257 A199773 * A304505 A210687 A000739

Adjacent sequences:  A245869 A245870 A245871 * A245873 A245874 A245875

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 04 2014

STATUS

approved

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Last modified July 14 19:48 EDT 2020. Contains 335729 sequences. (Running on oeis4.)