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
Keywords
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
Comments