A125397 Number of base 9 circular n-digit numbers with adjacent digits differing by 6 or less.

1, 9, 75, 597, 4999, 41959, 352605, 2963557, 24908879, 209361909, 1759712475, 14790602187, 124316856469, 1044898695889, 8782503978435, 73818042322837, 620449861007519, 5214958537443999, 43832377531943085, 368416605100242957

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+F(6) for base>=6.int(n/2)+1 and F(d) is the largest coefficient in (1+x+...+x^(2d))^n

Links

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

Formula

G.f.: (1 - 3*x^2 - 34*x^3 + 3*x^4 + 20*x^5) / ((1 + x)*(1 - x - x^2)*(1 - 9*x + 5*x^2)) (conjectured). - Colin Barker, Jun 02 2017

Prog

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>6)+($[(i+1)mod N]`-$[i]`>6))

Crossrefs

Sequence in context: A274311 A281804 A210045 * A095249 A190983 A254664

Adjacent sequences: A125394 A125395 A125396 * A125398 A125399 A125400

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved