A245947 Number of length n+3 0..5 arrays with some pair in every consecutive four terms totalling exactly 5.

834, 3966, 18384, 82968, 381222, 1744494, 7972932, 36489120, 166920402, 763564758, 3493201536, 15980209872, 73104350502, 334430964150, 1529917916484, 6998905422984, 32017855579074, 146471872453902, 670063969035792

Offset

1,1

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) + 13*a(n-3) - 13*a(n-4) - a(n-5) - 3*a(n-6) + a(n-7).

Empirical g.f.: 6*x*(139 + 244*x + 386*x^2 - 476*x^3 - 53*x^4 - 102*x^5 + 36*x^6) / (1 - 3*x - 5*x^2 - 13*x^3 + 13*x^4 + x^5 + 3*x^6 - x^7). - Colin Barker, Nov 05 2018

Example

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

Crossrefs

Column 5 of A245950.

Sequence in context: A095257 A236741 A113856 * A235288 A162945 A138850

Adjacent sequences: A245944 A245945 A245946 * A245948 A245949 A245950

Keyword

nonn

Author

R. H. Hardin, Aug 08 2014

Status

approved