A248460 Number of length n+2 0..7 arrays with no three consecutive terms having the sum of any two elements equal to twice the third

432, 2956, 20236, 138534, 948412, 6493036, 44452660, 304332258, 2083523194, 14264241960, 97656029050, 668573914642, 4577199017242, 31336476646048, 214536174915418, 1468760220688680, 10055444434320028, 68841708367472026

Offset

1,1

Comments

Column 7 of A248461

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 6*a(n-1) +9*a(n-2) -2*a(n-3) -109*a(n-4) -203*a(n-5) -4*a(n-6) +520*a(n-7) +1012*a(n-8) +696*a(n-9) +385*a(n-10) +373*a(n-11) -514*a(n-12) -2737*a(n-13) -4627*a(n-14) -3396*a(n-15) -2854*a(n-16) -3670*a(n-17) -2204*a(n-18) -634*a(n-19) -332*a(n-20) -162*a(n-21) -24*a(n-22)

Example

Some solutions for n=4
..0....4....7....2....1....2....0....6....1....7....0....4....1....4....0....0
..4....5....0....4....4....5....0....5....4....2....1....5....0....7....2....1
..4....2....7....5....0....6....3....5....1....0....4....2....7....3....7....5
..3....4....4....4....5....1....2....6....4....2....3....2....1....1....6....1
..7....7....3....0....6....5....6....0....1....2....7....7....5....0....6....2
..1....0....6....5....0....7....5....2....6....3....6....1....0....1....1....7

Crossrefs

Sequence in context: A006910 A015229 A360840 * A234327 A174717 A235418

Adjacent sequences: A248457 A248458 A248459 * A248461 A248462 A248463

Keyword

nonn

Author

R. H. Hardin, Oct 06 2014

Status

approved