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A126487
Number of base 19 n-digit numbers with adjacent digits differing by three or less.
2
1, 19, 121, 791, 5217, 34587, 230033, 1533159, 10233063, 68367029, 457062389, 3057032825, 20453043685, 136869404619, 916044100681, 6131521065627, 41043887722493, 274756556545945, 1839334652522085, 12313523619477007
OFFSET
0,2
COMMENTS
[Empirical] a(base,n)=a(base-1,n)+7^(n-1) for base>=3n-2; a(base,n)=a(base-1,n)+7^(n-1)-2 when base=3n-3.
FORMULA
G.f.: (1+8*x-64*x^2-36*x^3+236*x^4+91*x^5-231*x^6-80*x^7+63*x^8+18*x^9) / (1-11*x+24*x^2+48*x^3-96*x^4-77*x^5+96*x^6+49*x^7-27*x^8-9*x^9) (conjectured). - Colin Barker, Jul 18 2017
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))
CROSSREFS
Cf. Base 19 differing by two or less A126406, one or less A126373.
Sequence in context: A252054 A070302 A125329 * A241965 A182193 A109669
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 27 2006
STATUS
approved