A126402 Number of base 15 n-digit numbers with adjacent digits differing by two or less.

1, 15, 69, 325, 1543, 7361, 35223, 168899, 811105, 3899407, 18761375, 90319881, 434998065, 2095690739, 10098729091, 48672013183, 234609419433, 1130969299775, 5452365150693, 26286944474683, 126739125460983

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2.

Links

Table of n, a(n) for n=0..20.

Formula

G.f.: (1+6*x-46*x^2+14*x^3+102*x^4-25*x^5-52*x^6+5*x^7+2*x^8) / (1-9*x+20*x^2+10*x^3-46*x^4+x^5+23*x^6-x^7-x^8) (conjectured). - Colin Barker, Jul 18 2017

Prog

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

Crossrefs

Cf. Base 15 differing by one or less A126369.

Sequence in context: A212109 A124893 A352941 * A053134 A320917 A343871

Adjacent sequences: A126399 A126400 A126401 * A126403 A126404 A126405

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved