A221571 Number of 0..6 arrays of length n with each element differing from at least one neighbor by something other than 1.
0, 37, 197, 1369, 8991, 59705, 395641, 2622817, 17385993, 115249117, 763966685, 5064207645, 33569783613, 222528473325, 1475103973253, 9778217146445, 64818163521317, 429668748357261, 2848202159470085, 18880255015594493
Offset: 1
Keywords
Examples
Some solutions for n=6 ..4....2....5....0....4....4....2....3....1....3....6....0....5....4....0....2 ..6....5....1....2....4....6....5....5....4....1....6....2....0....6....6....2 ..2....5....6....5....5....2....2....5....1....0....2....3....0....5....1....5 ..4....4....6....2....3....3....5....6....1....0....6....1....6....1....5....1 ..6....2....0....5....4....1....1....6....1....0....0....3....4....3....5....4 ..6....4....2....5....1....5....6....4....4....4....4....0....2....3....3....2
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: -x^2*(37-62*x+138*x^2-26*x^3+100*x^4-36*x^5+48*x^6) / ( -1+7*x-4*x^2+6*x^3+26*x^4+10*x^5+16*x^6+12*x^8 ). - R. J. Mathar, Jun 06 2013
Comments