A221570 Number of 0..5 arrays of length n with each element differing from at least one neighbor by something other than 1.
0, 26, 114, 676, 3734, 20944, 117104, 655198, 3665306, 20505052, 114711980, 641737294, 3590092664, 20084178100, 112357602542, 628565969692, 3516408049766, 19671961528672, 110051525562128, 615665004273436
Offset: 1
Keywords
Examples
Some solutions for n=6 ..4....0....4....1....2....5....4....4....2....0....0....1....1....3....0....3 ..0....5....2....3....4....2....0....4....5....3....5....4....3....5....3....5 ..0....2....4....5....0....5....0....0....4....5....0....1....0....2....0....1 ..1....5....5....3....1....4....2....3....1....4....3....2....1....4....3....3 ..3....1....0....1....4....1....1....1....0....2....2....2....5....2....0....3 ..1....5....5....5....0....3....4....5....4....0....2....4....3....5....0....1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 5*a(n-1) +3*a(n-2) +9*a(n-4) +6*a(n-5) +3*a(n-6).
Empirical g.f.: -2*x^2*(13-8*x+14*x^2+6*x^3+6*x^4) / ( -1+5*x+3*x^2+9*x^4+6*x^5+3*x^6 ). - R. J. Mathar, Jun 06 2013
Comments