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%I #9 Jan 13 2014 10:42:16
%S 9,119,1229,12339,123449,1234559,12345669,123456779,12345678899,
%T 1234567890999,123456789101099,12345678910111199,1234567891011121299,
%U 123456789101112131399,12345678910111213141499,1234567891011121314151599,123456789101112131415161699
%N Numbers of the form 123...n - (n+1)
%e a(3) = 123 - 4 = 119.
%e a(4) = 1234 - 5 = 1229.
%e a(5) = 12345 - 6 = 12339.
%e etc.
%o (Python)
%o def Concatenate(x):
%o ..num = ''
%o ..for n in range(1,x+1):
%o ....num += str(n)
%o ..return int(num)
%o {print(Concatenate(x)-(x+1)) for x in range(1,50)}
%Y Cf. A007908.
%K nonn,base
%O 2,1
%A _Derek Orr_, Jan 02 2014
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