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A126395
Number of base 8 n-digit numbers with adjacent digits differing by two or less.
3
1, 8, 34, 150, 668, 2986, 13362, 59816, 267802, 1199022, 5368412, 24036226, 107618586, 481846232, 2157395218, 9659418342, 43248619100, 193639305850, 866991400098, 3881825980040, 17380302665002, 77817738944382
OFFSET
0,2
COMMENTS
[Empirical] a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2.
FORMULA
Conjectures from Colin Barker, Jun 01 2017: (Start)
G.f.: (1 + 3*x - 5*x^2 - 6*x^3) / (1 - 5*x + x^2 + 6*x^3).
a(n) = 5*a(n-1) - a(n-2) - 6*a(n-3) for n>3.
(End)
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>2)+($[i+1]`-$[i]`>2))
CROSSREFS
Cf. Base 8 differing by one or less A126362.
Sequence in context: A082840 A224240 A101644 * A335749 A227330 A252934
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
STATUS
approved