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A212836 Number of 0..n arrays of length 3 with 0 never adjacent to n. 1
2, 17, 50, 107, 194, 317, 482, 695, 962, 1289, 1682, 2147, 2690, 3317, 4034, 4847, 5762, 6785, 7922, 9179, 10562, 12077, 13730, 15527, 17474, 19577, 21842, 24275, 26882, 29669, 32642, 35807, 39170, 42737, 46514, 50507, 54722, 59165, 63842, 68759, 73922 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A212835.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = n^3 + 3*n^2 - n - 1.

Conjectures from Colin Barker, Jul 21 2018: (Start)

G.f.: x*(2 + 9*x - 6*x^2 + x^3) / (1 - x)^4.

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.

(End)

EXAMPLE

Some solutions for n=5:

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

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

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

CROSSREFS

Cf. A212835.

Sequence in context: A141860 A105691 A192345 * A125609 A100518 A125200

Adjacent sequences:  A212833 A212834 A212835 * A212837 A212838 A212839

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 28 2012

STATUS

approved

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Last modified November 18 10:08 EST 2019. Contains 329261 sequences. (Running on oeis4.)