login
Number of length-n 0..5 arrays with no adjacent pair x,x+1 repeated.
1

%I #4 Mar 02 2016 11:28:14

%S 6,36,216,1291,7686,45590,269472,1587450,9321628,54569340,318513432,

%T 1853885152,10761305560,62304937944,359833051280,2073213227007,

%U 11917692236634,68357220234784,391252708773072,2234836878469971

%N Number of length-n 0..5 arrays with no adjacent pair x,x+1 repeated.

%C Column 5 of A269656.

%H R. H. Hardin, <a href="/A269653/b269653.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 36*a(n-1) -570*a(n-2) +5244*a(n-3) -31353*a(n-4) +130248*a(n-5) -398332*a(n-6) +954000*a(n-7) -1897824*a(n-8) +3269288*a(n-9) -5011092*a(n-10) +6954336*a(n-11) -8842060*a(n-12) +10392360*a(n-13) -11368380*a(n-14) +11633264*a(n-15) -11177154*a(n-16) +10110960*a(n-17) -8629656*a(n-18) +6958872*a(n-19) -5305806*a(n-20) +3825752*a(n-21) -2608020*a(n-22) +1679472*a(n-23) -1020104*a(n-24) +583128*a(n-25) -312780*a(n-26) +156800*a(n-27) -73068*a(n-28) +31416*a(n-29) -12340*a(n-30) +4368*a(n-31) -1365*a(n-32) +364*a(n-33) -78*a(n-34) +12*a(n-35) -a(n-36)

%e Some solutions for n=6

%e ..0. .1. .3. .4. .4. .2. .5. .4. .2. .1. .3. .5. .4. .4. .1. .5

%e ..3. .5. .3. .3. .3. .0. .1. .4. .0. .3. .4. .1. .4. .0. .4. .1

%e ..3. .2. .4. .2. .0. .4. .4. .0. .5. .3. .0. .2. .2. .3. .0. .4

%e ..0. .5. .3. .0. .2. .1. .4. .4. .0. .2. .2. .1. .5. .5. .2. .0

%e ..1. .2. .5. .5. .3. .1. .4. .1. .5. .2. .5. .4. .0. .3. .1. .4

%e ..4. .5. .2. .4. .4. .0. .4. .1. .5. .5. .3. .1. .2. .3. .5. .1

%Y Cf. A269656.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 02 2016