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A126484
Number of base 16 n-digit numbers with adjacent digits differing by three or less.
2
1, 16, 100, 644, 4188, 27384, 179612, 1180228, 7763498, 51099608, 336460302, 2215852392, 14594879684, 96137054032, 633284508204, 4171739971970, 27481572723178, 181037861103928, 1192612216360274, 7856520861476702
OFFSET
0,2
COMMENTS
[Empirical] a(base,n)=a(base-1,n)+7^(n-1) for base>=3n-2; a(base,n)=a(base-1,n)+7^(n-1)-2 when base=3n-3.
FORMULA
G.f.: (1+6*x-41*x^2-22*x^3+83*x^4+6*x^5-39*x^6+x^7+4*x^8) / (1-10*x+19*x^2+30*x^3-45*x^4-14*x^5+21*x^6+x^7-2*x^8) (conjectured). - Colin Barker, Jul 18 2017
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))
CROSSREFS
Cf. Base 16 differing by two or less A126403, one or less A126370.
Sequence in context: A052206 A169721 A125326 * A091100 A061432 A376705
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 27 2006
STATUS
approved