A125422 Number of base 10 circular n-digit numbers with adjacent digits differing by 7 or less.

1, 10, 94, 850, 8022, 75830, 717388, 6787364, 64217998, 607594090, 5748711994, 54391069402, 514617618420, 4869021638192, 46067936415154, 435868830209930, 4123945024124830, 39018441749664142, 369170487886312636

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..18.

Formula

G.f.: (1 - 3*x^2 - 40*x^3 + 3*x^4 + 24*x^5) / ((1 - x - x^2)*(1 - 9*x - 5*x^2 + 6*x^3)) (conjectured). - Colin Barker, Jun 01 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: A281203 A369335 A126633 * A190988 A287830 A259289

Adjacent sequences: A125419 A125420 A125421 * A125423 A125424 A125425

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved