A126507 Number of base 12 n-digit numbers with adjacent digits differing by four or less.

1, 12, 88, 672, 5168, 39796, 306520, 2361008, 18186104, 140082072, 1079010248, 8311293248, 64019406944, 493122351856, 3798374049312, 29257739717488, 225363621979872, 1735908604096736, 13371185000068864, 102994240528644064

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+4*x-8*x^2-14*x^3+6*x^4+6*x^5) / (1-8*x+18*x^3-2*x^4-6*x^5) (conjectured). - Colin Barker, Jul 17 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 12 differing by three or less A126480, two or less A126399, one or less A126366.

Sequence in context: A164608 A081009 A155635 * A181704 A009657 A012088

Adjacent sequences: A126504 A126505 A126506 * A126508 A126509 A126510

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved