A269405 Number of length-n 0..4 arrays with no repeated value greater than or equal to the previous repeated value.

5, 25, 120, 570, 2670, 12380, 56890, 259445, 1175355, 5293671, 23718780, 105781845, 469798125, 2078552055, 9164402118, 40277785365, 176503698495, 771372344695, 3362640467600, 14624384170213, 63463229049585, 274836205944615

Offset: 1

Author

R. H. Hardin, Feb 25 2016

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 4 of A269409

Formula

Empirical: a(n) = 20*a(n-1) - 150*a(n-2) + 460*a(n-3) - 65*a(n-4) - 2472*a(n-5) + 2320*a(n-6) + 6400*a(n-7) - 3840*a(n-8) - 10240*a(n-9) - 4096*a(n-10).

Empirical g.f.: x*(5 - 75*x + 370*x^2 - 380*x^3 - 1905*x^4 + 3265*x^5 + 5590*x^6 - 5865*x^7 - 11455*x^8 - 4339*x^9) / ((1 + x)^4*(1 - 4*x)^6). - Colin Barker, Jan 21 2019