A126371 Number of base 17 n-digit numbers with adjacent digits differing by one or less.

1, 17, 49, 143, 419, 1231, 3623, 10677, 31497, 92991, 274727, 812089, 2401661, 7105541, 21029893, 62260511, 184377699, 546148863, 1618115031, 4795057355, 14212022443, 42129691565, 124906348517, 370372587127, 1098363570827

Offset

0,2

Comments

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

Links

Table of n, a(n) for n=0..24.

Formula

G.f.: (1+8*x-77*x^2+140*x^3+62*x^4-266*x^5+17*x^6+132*x^7-6*x^8-10*x^9) / ((1-x)*(1-2*x-2*x^2)*(1-6*x+9*x^2+4*x^3-12*x^4+x^6)) (conjectured). - Colin Barker, Jul 18 2017

Prog

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

Crossrefs

Sequence in context: A049737 A146871 A146791 * A342609 A146799 A147201

Adjacent sequences: A126368 A126369 A126370 * A126372 A126373 A126374

Keyword

nonn,base

Author

R. H. Hardin, Dec 26 2006

Status

approved