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A126405 Number of base 18 n-digit numbers with adjacent digits differing by two or less. 3
1, 18, 84, 400, 1918, 9236, 44598, 215774, 1045480, 5071280, 24620610, 119613534, 581435182, 2827574694, 13755641338, 66937791112, 325807794512, 1586104016732, 7722649252978, 37605625036546, 183139080847344 (list; graph; refs; listen; history; text; internal format)
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+8*x-70*x^2+39*x^3+220*x^4-61*x^5-172*x^6+22*x^7+36*x^8) / (1-10*x+26*x^2+11*x^3-80*x^4-x^5+60*x^6-2*x^7-12*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 18 differing by one or less A126372.

Sequence in context: A067984 A281372 A124935 * A250101 A141842 A215191

Adjacent sequences:  A126402 A126403 A126404 * A126406 A126407 A126408

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 28 2006

STATUS

approved

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Last modified September 30 07:52 EDT 2022. Contains 357104 sequences. (Running on oeis4.)