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%I #62 Oct 25 2022 10:19:54
%S 1,12,123,1234,12345,123456,1234567,12345678,123456789,1234567891,
%T 12345678910,123456789101,1234567891011,12345678910111,
%U 123456789101112,1234567891011121,12345678910111213,123456789101112131,1234567891011121314
%N a(n) is the concatenation of first n terms of A033307.
%H Harvey P. Dale, <a href="/A252043/b252043.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = floor(C*10^n) with C the Champernowne constant, 0.123456789101112131415..., A033307.
%F a(n) = floor(A007908(n)/10^n) For n>=10.
%e a(3)=123.
%p a[0]:= 0;
%p count:= 0:
%p for x from 1 to 30 do
%p L:= convert(x,base,10);
%p for i from 1 to nops(L) do
%p count:= count+1;
%p a[count]:= a[count-1]*10+L[-i];
%p od
%p od:
%p seq(a[i],i=1..count); # _Robert Israel_, Jan 11 2015
%t b[1] = 1
%t b[n_] := b[n - 1]*10^(Floor[Log[10, 10n]]) + n
%t Table[Floor[b[n] /10^(n)], {n, 10, 200}]
%t Module[{nn=20,ch},ch=RealDigits[ChampernowneNumber[],10,nn][[1]];Table[ FromDigits[ Take[ch,n]],{n,nn}]] (* _Harvey P. Dale_, Aug 31 2015 *)
%o (Python)
%o from itertools import islice
%o def bgen(): yield from (c for n in count(1) for c in str(n) )
%o def agen():
%o s, g = "", bgen()
%o while True:
%o s += next(g); yield int(s)
%o print(list(islice(agen(), 20))) # _Michael S. Branicky_, Oct 25 2022
%Y Cf. A007908 (concatenate 1 through n), A033307.
%K nonn,base
%O 1,2
%A _José de Jesús Camacho Medina_, Dec 15 2014
%E Definition corrected by _Zak Seidov_, Jan 18 2015
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