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A126400
Number of base 13 n-digit numbers with adjacent digits differing by two or less.
3
1, 13, 59, 275, 1293, 6111, 28973, 137649, 654857, 3118273, 14857419, 70818391, 337647601, 1610116861, 7678944363, 36625115213, 174694226717, 833283367207, 3974811512311, 18960367898651, 90444302124667, 431438069091899
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.
FORMULA
G.f.: (1+5*x-31*x^2-3*x^3+50*x^4-3*x^5-18*x^6) / ((1-x)*(1-7*x+7*x^2+19*x^3-6*x^4-9*x^5)) (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 13 differing by one or less A126367.
Sequence in context: A163833 A213567 A124864 * A297962 A354670 A220711
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
STATUS
approved