A248437 Number of length 4+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.
2, 9, 28, 101, 198, 327, 462, 691, 932, 1203, 1474, 1829, 2184, 2551, 2954, 3459, 3964, 4501, 5038, 5653, 6286, 6925, 7564, 8327, 9114, 9907, 10712, 11577, 12442, 13363, 14284, 15307, 16342, 17383, 18454, 19609, 20764, 21925, 23098, 24389, 25680, 27009
Offset: 1
Keywords
Examples
Some solutions for n=6 ..4....1....3....1....5....3....2....6....5....4....3....2....5....3....5....1 ..5....5....4....3....3....1....4....2....4....2....5....1....4....3....1....3 ..6....3....2....2....1....2....0....4....6....0....1....3....6....3....3....5 ..4....4....3....1....2....0....2....0....2....4....3....2....2....3....5....1 ..2....2....1....0....3....4....1....2....4....2....2....4....4....3....4....3 ..0....3....5....2....4....2....3....4....0....3....4....3....6....3....6....5
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = -a(n-4) +a(n-5) +a(n-7) -a(n-8) +a(n-9) +a(n-11) -a(n-12) +a(n-13) +a(n-15) -a(n-21) -a(n-23) +a(n-24) -a(n-25) -a(n-27) +a(n-28) -a(n-29) -a(n-31) +a(n-32) +a(n-36)
Comments