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4, 32, 284, 2552, 22964, 206672, 1860044, 16740392, 150663524, 1355971712, 12203745404, 109833708632, 988503377684, 8896530399152, 80068773592364, 720618962331272, 6485570660981444, 58370135948832992, 525331223539496924
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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LINKS
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FORMULA
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a(n) = 9*a(n-1)-4.
a(n) = 10*a(n-1)-9*a(n-2).
G.f.: 4*(1-2*x)/((1-x)*(1-9*x)).
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MATHEMATICA
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(7*9^Range[0, 20]+1)/2 (* or *) LinearRecurrence[{10, -9}, {4, 32}, 20] (* Harvey P. Dale, Dec 08 2012 *)
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PROG
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(Magma) [(7*9^n+1)/2: n in [0..30]];
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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