A247527 Number of length n+3 0..2 arrays with some disjoint pairs in every consecutive four terms having the same sum.

33, 45, 61, 81, 105, 153, 217, 297, 393, 585, 841, 1161, 1545, 2313, 3337, 4617, 6153, 9225, 13321, 18441, 24585, 36873, 53257, 73737, 98313, 147465, 213001, 294921, 393225, 589833, 851977, 1179657, 1572873, 2359305, 3407881, 4718601, 6291465

Offset: 1

Author

R. H. Hardin, Sep 18 2014

Keywords

• nonn

Examples

			Some solutions for n=6:
..2....1....0....2....0....2....0....0....1....1....0....0....2....1....1....2
..1....0....1....1....1....1....1....1....0....1....2....0....1....2....2....1
..0....2....0....0....0....1....1....1....2....0....1....1....1....0....2....1
..1....1....1....1....1....0....0....0....1....2....1....1....2....1....1....2
..2....1....2....2....2....2....0....0....1....1....2....2....0....1....1....0
..1....0....1....1....1....1....1....1....2....1....2....2....1....2....0....1
..2....2....2....0....2....1....1....1....0....2....1....1....1....0....2....1
..1....1....1....1....1....0....0....0....1....2....1....1....2....1....1....0
..2....1....0....0....2....2....2....0....1....1....0....0....0....1....1....2
		

Links

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

Crossrefs

Column 2 of A247533.

Formula

Empirical: a(n) = a(n-1) + 4*a(n-4) - 4*a(n-5).

Empirical g.f.: x*(33 + 12*x + 16*x^2 + 20*x^3 - 108*x^4) / ((1 - x)*(1 - 2*x^2)*(1 + 2*x^2)). - Colin Barker, Nov 07 2018