A221540 Number of 0..6 arrays of length n with each element differing from at least one neighbor by something other than 1, starting with 0.
0, 6, 32, 222, 1455, 9665, 64047, 424593, 2814515, 18656979, 123673887, 819813575, 5434406883, 36023773275, 238795558499, 1582935756291, 10493015970771, 69556445196155, 461078023878243, 3056408985571563, 20260423189286435
Offset: 1
Keywords
Examples
Some solutions for n=6 ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0 ..6....5....2....4....5....2....0....0....5....6....3....0....2....0....5....4 ..2....2....6....1....2....1....0....6....6....6....5....6....0....4....1....0 ..5....2....0....6....2....1....2....2....6....3....1....3....3....3....0....6 ..5....6....0....5....6....5....6....0....6....4....5....5....4....1....3....6 ..2....6....0....3....0....0....4....4....0....1....3....1....0....6....3....4
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 7*a(n-1) -4*a(n-2) +6*a(n-3) +26*a(n-4) +10*a(n-5) +16*a(n-6) +12*a(n-8).
Empirical g.f.: x^2*(6 - 10*x + 22*x^2 - 7*x^3 + 20*x^4 - 12*x^5 + 6*x^6) / (1 - 7*x + 4*x^2 - 6*x^3 - 26*x^4 - 10*x^5 - 16*x^6 - 12*x^8). - Colin Barker, Oct 18 2017
Comments