A125423 Number of base 11 circular n-digit numbers with adjacent digits differing by 7 or less.

1, 11, 109, 1019, 10157, 101661, 1019443, 10225933, 102583621, 1029106379, 10323909799, 103568694097, 1038993624419, 10423109098179, 104563879665711, 1048977311016399, 10523264850876341, 105568635251351455

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+F(7) for base>=7.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..17.

Formula

G.f.: (1 - 6*x^2 - 76*x^3 + 15*x^4 + 108*x^5 - 5*x^6 - 30*x^7) / ((1 - 2*x - x^2 + x^3)*(1 - 9*x - 11*x^2 + 6*x^3 + 5*x^4)) (conjectured). - Colin Barker, Jun 04 2017

Prog

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>7)+($[(i+1)mod N]`-$[i]`>7))

Crossrefs

Sequence in context: A071380 A142423 A159495 * A165149 A048346 A054320

Adjacent sequences: A125420 A125421 A125422 * A125424 A125425 A125426

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved