A126512 Number of base 17 n-digit numbers with adjacent digits differing by four or less.

1, 17, 133, 1077, 8813, 72489, 597605, 4931789, 40718813, 336260155, 2777127335, 22936867057, 189443806193, 1564697193813, 12923549080107, 106741672742177, 881630348819317, 7281807635192719, 60143948424783609, 496757803961266447

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

Table of n, a(n) for n=0..19.

Formula

G.f.: (1+7*x-30*x^2-74*x^3+7*x^4+56*x^5+10*x^6-8*x^7-2*x^8) / (1-10*x+7*x^2+60*x^3+13*x^4-43*x^5-14*x^6+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]`-$[i+1]`>4)+($[i+1]`-$[i]`>4))

Crossrefs

Cf. Base 17 differing by three or less A126485, two or less A126404, one or less A126371.

Sequence in context: A253416 A275483 A125354 * A297018 A196783 A047642

Adjacent sequences: A126509 A126510 A126511 * A126513 A126514 A126515

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved