A126481 Number of base 13 n-digit numbers with adjacent digits differing by three or less.

1, 13, 79, 497, 3159, 20181, 129205, 828005, 5308457, 34039495, 218289367, 1399900567, 8977768487, 57576133509, 369247743009, 2368065719909, 15186926536617, 97397125090807, 624629410666375, 4005887424197615

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+7^(n-1) for base>=3n-2; a(base,n)=a(base-1,n)+7^(n-1)-2 when base=3n-3.

Links

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

Formula

G.f.: (1+5*x-19*x^2-29*x^3+16*x^4+20*x^5-2*x^6-2*x^7) / (1-8*x+6*x^2+28*x^3-5*x^4-18*x^5+2*x^7) (conjectured). - Colin Barker, Jul 18 2017

Prog

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))

Crossrefs

Cf. Base 13 differing by two or less A126400, one or less A126367.

Sequence in context: A081584 A125323 A075584 * A032625 A120782 A032652

Adjacent sequences: A126478 A126479 A126480 * A126482 A126483 A126484

Keyword

nonn,base

Author

R. H. Hardin, Dec 27 2006

Status

approved