A246000 Number of length 5+2 0..n arrays with no pair in any consecutive three terms totalling exactly n.
2, 38, 956, 7132, 40590, 153906, 496088, 1319480, 3178490, 6857470, 13855572, 26075028, 46848326, 80108042, 132346160, 210837616, 327085938, 493492950, 729039980, 1053585740, 1496758142, 2088821218, 2874009096, 3896630952
Offset: 1
Keywords
Examples
Some solutions for n=6 ..4....4....0....2....1....0....3....3....0....4....1....0....3....3....4....4 ..5....6....2....2....1....0....1....5....5....5....3....2....4....6....4....5 ..6....5....1....5....2....0....1....5....5....0....4....0....1....4....4....4 ..4....3....1....0....1....5....6....5....0....2....6....0....3....4....4....3 ..6....5....1....2....1....2....3....5....4....5....3....0....4....0....1....1 ..4....0....4....0....4....3....1....3....0....6....5....5....0....1....3....4 ..3....2....6....1....3....6....4....2....5....6....5....3....5....4....2....4
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 3*a(n-1) +2*a(n-2) -14*a(n-3) +5*a(n-4) +25*a(n-5) -20*a(n-6) -20*a(n-7) +25*a(n-8) +5*a(n-9) -14*a(n-10) +2*a(n-11) +3*a(n-12) -a(n-13)
Comments