A221464 Number of 0..n arrays of length 5 with each element unequal to at least one neighbor, starting with 0.

3, 32, 135, 384, 875, 1728, 3087, 5120, 8019, 12000, 17303, 24192, 32955, 43904, 57375, 73728, 93347, 116640, 144039, 176000, 213003, 255552, 304175, 359424, 421875, 492128, 570807, 658560, 756059, 864000, 983103, 1114112, 1257795

Offset: 1

Author

R. H. Hardin, Jan 17 2013

Keywords

• nonn

Comments

Row 5 of A221463.

Examples

			Some solutions for n=6:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..5....6....3....4....4....1....1....4....5....3....4....4....5....6....5....6
..0....6....1....5....5....5....3....5....1....3....0....4....5....4....3....0
..2....5....2....5....5....3....0....3....0....4....0....3....2....0....2....2
..5....0....1....4....2....0....4....5....6....3....1....2....0....6....0....4
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..137

Crossrefs

Cf. A221463.

Formula

Empirical: a(n) = 1*n^4 + 2*n^3.

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

G.f.: x*(3 + 17*x + 5*x^2 - x^3) / (1 - x)^5.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>5.

(End)