A125470 Number of base 13 circular n-digit numbers with adjacent digits differing by 9 or less.

1, 13, 157, 1813, 21997, 267483, 3255907, 39636855, 482546341, 5874634345, 71519267407, 870693584543, 10600043444419, 129047604857977, 1571058121063511, 19126458200814873, 232850330879455797

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+F(9) for base>=9.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..16.

Formula

G.f.: (1-6*x^2-100*x^3+15*x^4+148*x^5-5*x^6-42*x^7) / ((1-2*x-x^2+x^3)*(1-11*x-15*x^2+8*x^3+7*x^4)) (conjectured). - Colin Barker, Jul 18 2017

Prog

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>9)+($[(i+1)mod N]`-$[i]`>9))

Crossrefs

Sequence in context: A360192 A244206 A159499 * A165151 A016125 A353147

Adjacent sequences: A125467 A125468 A125469 * A125471 A125472 A125473

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved