A126483 Number of base 15 n-digit numbers with adjacent digits differing by three or less.

1, 15, 93, 595, 3845, 24983, 162805, 1062635, 6941843, 45369865, 296598577, 1939229883, 12680054343, 82914396455, 542185539797, 3545445779213, 23184429833549, 151608454599649, 991405196934357, 6483050068051005

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+6*x-31*x^2-40*x^3+48*x^4+35*x^5-19*x^6-5*x^7+2*x^8) / (1-9*x+11*x^2+37*x^3-20*x^4-29*x^5+8*x^6+4*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]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))

Crossrefs

Cf. Base 15 differing by two or less A126402, one or less A126369.

Sequence in context: A052226 A108684 A125325 * A226766 A114240 A189657

Adjacent sequences: A126480 A126481 A126482 * A126484 A126485 A126486

Keyword

nonn,base

Author

R. H. Hardin, Dec 27 2006

Status

approved