A124167 a(n) = 10*(10^n-1).
0, 90, 990, 9990, 99990, 999990, 9999990, 99999990, 999999990, 9999999990, 99999999990, 999999999990, 9999999999990, 99999999999990, 999999999999990, 9999999999999990, 99999999999999990, 999999999999999990
Offset: 0
Links
- Michael De Vlieger, Table of n, a(n) for n = 0..999
- Index entries for linear recurrences with constant coefficients, signature (11,-10).
Programs
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GAP
List([0..20], n-> 10*(10^n -1)); # G. C. Greubel, Jun 30 2019
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Magma
[10*(10^n -1): n in [0..20]]; // G. C. Greubel, Jun 30 2019
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Maple
a:=n->sum (10^(n-j+2)-10^(n-j+1),j=0..n): seq(a(n),n=0..20);
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Mathematica
Array[10 (10^# - 1) &, 20, 0] (* Michael De Vlieger, Apr 21 2019 *)
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PARI
vector(20, n, n--; 10*(10^n -1)) \\ G. C. Greubel, Jun 30 2019
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Sage
[10*(10^n -1) for n in (0..20)] # G. C. Greubel, Jun 30 2019
Formula
a(n) = 10*A002283(n).
From G. C. Greubel, Jun 30 2019: (Start)
a(n) = 90*A002275(n).
a(n) = 11*a(n-1) - 10*a(n-2).
G.f.: 10*(1/(1-10*x) - 1/(1-x)).
E.g.f.: 10*(exp(10*x) - exp(x)). (End)
Comments