A255043 a(n) = (5*9^n - 1)/2.
2, 22, 202, 1822, 16402, 147622, 1328602, 11957422, 107616802, 968551222, 8716961002, 78452649022, 706073841202, 6354664570822, 57191981137402, 514727830236622, 4632550472129602, 41692954249166422, 375236588242497802, 3377129294182480222
Offset: 0
Links
- G. C. Greubel, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (10,-9).
Programs
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Magma
[(5*9^n -1)/2: n in [0..20]]; // G. C. Greubel, Feb 07 2021
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Mathematica
Table[(5*9^n - 1)/2, {n, 0, 19}] LinearRecurrence[{10,-9},{2,22},20] (* Harvey P. Dale, Jun 15 2018 *) -
Sage
[(5*9^n -1)/2 for n in (0..20)] # G. C. Greubel, Feb 07 2021
Formula
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.
a(n) = 2*A138894(n).
E.g.f.: (5*exp(9*x) - exp(x))/2. - G. C. Greubel, Feb 07 2021