A248430 Number of length n+2 0..5 arrays with every three consecutive terms having the sum of some two elements equal to twice the third.

42, 70, 118, 198, 342, 590, 1014, 1766, 3062, 5286, 9222, 16006, 27654, 48262, 83782, 144774, 252678, 438662, 758022, 1323014, 2296838, 3969030, 6927366, 12026374, 20782086, 36272134, 62970886, 108816390, 189923334, 329719814, 569769990

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 6*a(n-3) - 6*a(n-4) - 4*a(n-6) + 4*a(n-7).

Empirical g.f.: 2*x*(21 + 14*x + 24*x^2 - 86*x^3 - 12*x^4 - 20*x^5 + 56*x^6) / ((1 - x)*(1 - 6*x^3 + 4*x^6)). - Colin Barker, Nov 08 2018

Example

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

Crossrefs

Column 5 of A248433.

Sequence in context: A192274 A291319 A226168 * A340384 A330893 A305153

Adjacent sequences: A248427 A248428 A248429 * A248431 A248432 A248433

Keyword

nonn

Author

R. H. Hardin, Oct 06 2014

Status

approved