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A125344
Number of base 7 circular n-digit numbers with adjacent digits differing by 4 or less.
0
1, 7, 43, 247, 1527, 9497, 59245, 369803, 2308687, 14413783, 89990323, 561842893, 3507795765, 21900487967, 136732988323, 853675514807, 5329817595487, 33276057627697, 207754954396765, 1297092388823683, 8098236068810727
OFFSET
0,2
COMMENTS
[Empirical] a(base,n)=a(base-1,n)+A025014(n+1) for base>=4.int(n/2)+1.
FORMULA
G.f.: (1 - 3*x^2 - 22*x^3 + 3*x^4 + 12*x^5) / ((1 - x - x^2)*(1 - 6*x - 2*x^2 + 3*x^3)) (conjectured). - Colin Barker, Jun 03 2017
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>4)+($[(i+1)mod N]`-$[i]`>4))
CROSSREFS
Sequence in context: A081896 A363413 A193656 * A163869 A043553 A049609
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
STATUS
approved