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A124851 Number of base 9 circular n-digit numbers with adjacent digits differing by 2 or less. 1
1, 9, 39, 141, 587, 2479, 10731, 47063, 208547, 931047, 4180239, 18849103, 85269011, 386687375, 1756855951, 7993210831, 36405316227, 165940691695, 756832203759, 3453347063599, 15762537566627, 71964915505967 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

[Empirical] a(base,n)=a(base-1,n)+A005191(n+1) for base>=2.int(n/2)+1

LINKS

Table of n, a(n) for n=0..21.

FORMULA

G.f.: (1 - 21*x^2 - 14*x^3 + 150*x^4 - 16*x^5 - 150*x^6 + 24*x^7 + 28*x^8) / ((1 + x)*(1 - 4*x + 2*x^2)*(1 - 6*x + 5*x^2 + 8*x^3 - 4*x^4 - 2*x^5)) (conjectured). - Colin Barker, Jun 02 2017

PROG

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

CROSSREFS

Sequence in context: A060929 A212143 A294845 * A317019 A124041 A264085

Adjacent sequences:  A124848 A124849 A124850 * A124852 A124853 A124854

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 28 2006

STATUS

approved

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Last modified December 10 18:10 EST 2019. Contains 329901 sequences. (Running on oeis4.)