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A126403
Number of base 16 n-digit numbers with adjacent digits differing by two or less.
3
1, 16, 74, 350, 1668, 7986, 38348, 184524, 889230, 4290030, 20714382, 100083072, 483793208, 2339478320, 11316186924, 54748710158, 264922095330, 1282082867386, 6205185792886, 30034782040334, 145384379570694
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
G.f.: (1+7*x-51*x^2+4*x^3+131*x^4+10*x^5-61*x^6-2*x^7+3*x^8) / (1-9*x+19*x^2+16*x^3-49*x^4-14*x^5+23*x^6+2*x^7-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]`-$[i+1]`>2)+($[i+1]`-$[i]`>2))
CROSSREFS
Cf. Base 16 differing by one or less A126370.
Sequence in context: A058333 A232337 A124894 * A197873 A232863 A200786
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
STATUS
approved