|
| |
|
|
A126503
|
|
Number of base 8 n-digit numbers with adjacent digits differing by four or less.
|
|
1
|
|
|
|
1, 8, 52, 348, 2322, 15500, 103462, 690610, 4609826, 30770620, 205394096, 1371006978, 9151480836, 61086196378, 407750773322, 2721739165358, 18167627307952, 121269034961780, 809471627267722, 5403228578160660
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,2
|
|
|
COMMENTS
|
[Empirical] a(base,n)=a(base-1,n)+9^(n-1) for base>=4n-3; a(base,n)=a(base-1,n)+9^(n-1)-2 when base=4n-4.
|
|
|
LINKS
|
|
|
|
FORMULA
|
G.f.: (1 + 2*x - x^2 - x^3) / (1 - 6*x - 5*x^2 + 3*x^3 + 2*x^4).
a(n) = 6*a(n-1) + 5*a(n-2) - 3*a(n-3) - 2*a(n-4) for n>3.
(End)
|
|
|
PROG
|
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>4)+($[i+1]`-$[i]`>4))
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn,base
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
