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A126485
Number of base 17 n-digit numbers with adjacent digits differing by three or less.
2
1, 17, 107, 693, 4531, 29785, 196419, 1297863, 8586301, 56847741, 376551555, 2494950507, 16533981983, 109582499195, 726331242669, 4814449605487, 31913168495095, 211543760702517, 1402280350135071, 9295487072185279
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+7*x-46*x^2-44*x^3+118*x^4+63*x^5-89*x^6-27*x^7+18*x^8) / ((1-x)*(1-9*x+8*x^2+52*x^3+2*x^4-49*x^5-9*x^6+9*x^7)) (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 17 differing by two or less A126404, one or less A126371.
Sequence in context: A142321 A007682 A125327 * A159031 A080441 A135400
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 27 2006
STATUS
approved