A246486 Number of length 7+3 0..n arrays with no pair in any consecutive four terms totalling exactly n.

2, 72, 6908, 87888, 1309038, 8628792, 53733080, 226048032, 881180090, 2758803240, 8099880852, 20739933552, 50471282918, 111972509208, 238609813808, 475857371712, 918806537970, 1688132007432, 3020848830380, 5201549128080

Offset

1,1

Comments

Row 7 of A246479.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +5*a(n-2) -23*a(n-3) -4*a(n-4) +76*a(n-5) -28*a(n-6) -140*a(n-7) +98*a(n-8) +154*a(n-9) -154*a(n-10) -98*a(n-11) +140*a(n-12) +28*a(n-13) -76*a(n-14) +4*a(n-15) +23*a(n-16) -5*a(n-17) -3*a(n-18) +a(n-19).

Example

Some solutions for n=4
..1....0....4....2....1....2....4....1....0....2....3....0....2....3....3....4
..0....0....3....4....1....4....1....1....2....1....3....3....3....0....2....1
..0....2....3....1....1....3....1....1....3....0....0....0....3....0....0....2
..2....1....3....1....2....3....1....2....3....0....3....2....0....0....3....4
..1....1....0....1....0....3....4....0....3....0....3....3....2....1....0....1
..1....1....0....1....0....3....4....1....4....1....3....3....0....0....2....1
..1....4....0....1....3....4....1....0....3....0....3....4....0....2....0....1
..4....4....2....1....0....2....2....2....2....1....0....4....3....0....0....2
..1....1....0....1....0....4....1....0....3....2....3....4....3....1....3....1
..2....2....1....0....3....4....0....3....0....0....0....2....3....1....3....0

Crossrefs

Cf. A246479.

Sequence in context: A344056 A253316 A051443 * A123072 A351764 A317346

Adjacent sequences: A246483 A246484 A246485 * A246487 A246488 A246489

Keyword

nonn

Author

R. H. Hardin, Aug 27 2014

Status

approved