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A255043
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a(n) = (5*9^n - 1)/2.
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2
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2, 22, 202, 1822, 16402, 147622, 1328602, 11957422, 107616802, 968551222, 8716961002, 78452649022, 706073841202, 6354664570822, 57191981137402, 514727830236622, 4632550472129602, 41692954249166422, 375236588242497802, 3377129294182480222
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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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G.f.: 2*(1+x)/((1-x)*(1-9*x)).
Recurrence: a(n) = 10*a(n-1) - 9*a(n-2), n>=2, a(0) = 2, a(1) = 22.
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MATHEMATICA
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Table[(5*9^n - 1)/2, {n, 0, 19}]
LinearRecurrence[{10, -9}, {2, 22}, 20] (* Harvey P. Dale, Jun 15 2018 *)
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PROG
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(Sage) [(5*9^n -1)/2 for n in (0..20)] # G. C. Greubel, Feb 07 2021
(Magma) [(5*9^n -1)/2: n in [0..20]]; // G. C. Greubel, Feb 07 2021
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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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