A201083 Number of -3..3 arrays of n elements with first and second differences also in -3..3.

7, 37, 153, 651, 2771, 11817, 50391, 214867, 916173, 3906507, 16657167, 71025391, 302848889, 1291333199, 5506183213, 23478102983, 100109512887, 426862194475, 1820120064499, 7760905257671, 33092130346043, 141103267528637

Offset: 1

Author

R. H. Hardin Nov 26 2011

Keywords

• nonn

Comments

Column 3 of A201088.

Examples

			Some solutions for n=7
..0...-1...-2...-3....1....1...-3....3....2....0....0....2....2...-2....2....0
..0...-1....0...-3....0....2....0....1....3....3....3....1...-1...-2....2....1
.-1....2....3...-1....0....1....0...-1....2....3....3....1...-1...-1...-1....0
.-3....3....3....0....3....0...-1...-2....1....0....2....2...-1....2...-2....1
.-3....1....3....2....3...-2...-1....0....2....0....3....0....1....2...-1....0
.-2....1....0....1....3...-1....2....1....2....1....1...-2....0....2....2...-2
.-1....1...-3...-2....0....0....2....3....1....0....1...-2....2...-1....2...-2
		

Links

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

Crossrefs

Cf. A201088.

Formula

Empirical: a(n) = 4*a(n-1) -a(n-2) +8*a(n-3) +4*a(n-4) +3*a(n-5) -2*a(n-6) -3*a(n-7) -7*a(n-8) -4*a(n-9) +7*a(n-10) +8*a(n-11) +3*a(n-12) -3*a(n-13) -2*a(n-14) +a(n-15) +2*a(n-16) +a(n-17).