OFFSET
1,1
COMMENTS
Column 3 of A233997.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
Robert Israel, Linear recurrence of order 292.
EXAMPLE
Some solutions for n=4:
0 5 0 2 3 6 3 0 4 1 3 6 4 1 1 4 2 5 0 3
5 6 5 5 6 1 6 3 1 6 6 1 1 6 0 5 1 6 5 0
0 5 0 6 3 6 3 0 6 3 1 4 6 3 3 0 1 0 5 2
1 4 1 1 0 3 0 5 1 6 6 1 1 6 0 5 1 6 5 0
6 1 6 0 3 6 3 0 3 6 0 1 2 5 5 6 1 0 5 2
MAPLE
good:=select(proc(t) local i, j; add(add(abs(t[i]-t[j]), j=i+1..4), i=1..3)=18 end proc, [seq(seq(seq(seq([a, b, c, d], a=0..6), b=0..6), c=0..6), d=0..6)]):
good2:= convert(map(t -> t[1..2], good), set):
configs:= select(t -> member([t[1][2], t[2][1]], good2),
{seq(seq([t1, t2], t1=good2), t2=good2)]:
N:= nops(configs):
T:= Matrix(N, N, proc(i, j) local k; if
{seq([op(configs[i][k..k+1]), op(configs[j][k..k+1])], k=1..3)} subset good then 1 else 0 fi end proc):
e:= Vector(N, 1):
u[0]:= e:
for i from 1 to 30 do
u[i]:= T . u[i-1]
od:
seq(e^%T . u[i], i=1..30); # Robert Israel, Dec 25 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 18 2013
STATUS
approved