A126485 Number of base 17 n-digit numbers with adjacent digits differing by three or less.

1, 17, 107, 693, 4531, 29785, 196419, 1297863, 8586301, 56847741, 376551555, 2494950507, 16533981983, 109582499195, 726331242669, 4814449605487, 31913168495095, 211543760702517, 1402280350135071, 9295487072185279

Offset

0,2

Comments

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

Links

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

Formula

G.f.: (1+7*x-46*x^2-44*x^3+118*x^4+63*x^5-89*x^6-27*x^7+18*x^8) / ((1-x)*(1-9*x+8*x^2+52*x^3+2*x^4-49*x^5-9*x^6+9*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 17 differing by two or less A126404, one or less A126371.

Sequence in context: A142321 A007682 A125327 * A387828 A159031 A080441

Adjacent sequences: A126482 A126483 A126484 * A126486 A126487 A126488

Keyword

nonn,base,more

Author

R. H. Hardin, Dec 27 2006

Status

approved