A202118 Number of -2..2 arrays of n elements with first, second and third differences also in -2..2.

5, 19, 57, 127, 293, 663, 1517, 3459, 7905, 18051, 41239, 94203, 215217, 491661, 1123219, 2566023, 5862189, 13392389, 30595439, 69896451, 159681185, 364797903, 833395099, 1903923685, 4349588175, 9936804401, 22701018621, 51861365563

Offset: 1

Author

R. H. Hardin Dec 11 2011

Keywords

• nonn

Comments

Column 2 of A202124

Examples

			Some solutions for n=7
..1...-1...-1....1....1....1...-2....1....0....2...-2...-2....0....1....1....0
..0...-2...-2....1...-1....1....0....1....2....2....0...-2...-1....0....1...-1
..0...-2...-2....2...-1....0....0....2....2....1....2...-1...-1....0....0...-2
.-1...-2...-1....2...-1....0....0....2....2....1....2....0...-1....1....0...-1
.-1....0....1....2...-1...-1....1....2....1....0....1....1....0....1....0....0
.-1....2....2....1...-1...-2....2....0...-1...-1....1....1....0....1....0....0
..1....2....1....1...-1...-2....2...-2...-2....0....2....0....1....2...-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-3) +3*a(n-4) -2*a(n-5) -3*a(n-6) -4*a(n-7) -3*a(n-8) -2*a(n-9) +3*a(n-10) +4*a(n-11) +2*a(n-12) for n>17