A245160 Number of length n 0..5 arrays with new values introduced in order from both ends.

1, 1, 2, 4, 9, 23, 65, 199, 654, 2296, 8569, 33825, 140580, 612890, 2794159, 13280627, 65597882, 335521900, 1770176005, 9593485125, 53183385680, 300371056446, 1721926382427, 9987133305239, 58446578859494, 344361988828048

Offset: 1

Author

R. H. Hardin, Jul 12 2014

Keywords

• nonn

Examples

			Some solutions for n=7:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..0....1....1....1....1....1....1....1....0....1....0....1....1....1....1....0
..1....2....1....0....0....0....0....0....1....2....1....0....0....2....1....1
..0....2....0....0....2....1....0....1....2....2....2....0....1....2....2....2
..2....2....0....0....0....0....0....0....0....0....1....1....1....1....2....2
..1....1....1....0....1....1....1....0....1....1....0....0....0....0....1....1
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
		

Links

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

Crossrefs

Column 5 of A245163.

Formula

Empirical: a(n) = 26*a(n-1) - 290*a(n-2) + 1820*a(n-3) - 7073*a(n-4) + 17618*a(n-5) - 28060*a(n-6) + 27480*a(n-7) - 14976*a(n-8) + 3456*a(n-9) for n>10.

Empirical g.f.: x*(1 - 25*x + 266*x^2 - 1578*x^3 + 5738*x^4 - 13236*x^5 + 19385*x^6 - 17565*x^7 + 9271*x^8 - 2381*x^9) / ((1 - x)^2*(1 - 2*x)^2*(1 - 3*x)^2*(1 - 4*x)^2*(1 - 6*x)). - Colin Barker, Nov 03 2018