A252043 a(n) is the concatenation of first n terms of A033307.

1, 12, 123, 1234, 12345, 123456, 1234567, 12345678, 123456789, 1234567891, 12345678910, 123456789101, 1234567891011, 12345678910111, 123456789101112, 1234567891011121, 12345678910111213, 123456789101112131, 1234567891011121314

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = floor(C*10^n) with C the Champernowne constant, 0.123456789101112131415..., A033307.

a(n) = floor(A007908(n)/10^n) For n>=10.

Example

a(3)=123.

Maple

a[0]:= 0;
count:= 0:
for x from 1 to 30 do
  L:= convert(x, base, 10);
  for i from 1 to nops(L) do
    count:= count+1;
    a[count]:= a[count-1]*10+L[-i];
  od
od:
seq(a[i], i=1..count); # Robert Israel, Jan 11 2015

Mathematica

b[1] = 1
b[n_] := b[n - 1]*10^(Floor[Log[10, 10n]]) + n
Table[Floor[b[n] /10^(n)], {n, 10, 200}]
Module[{nn=20, ch}, ch=RealDigits[ChampernowneNumber[], 10, nn][[1]]; Table[ FromDigits[ Take[ch, n]], {n, nn}]] (* Harvey P. Dale, Aug 31 2015 *)

Prog

(Python)
from itertools import islice
def bgen(): yield from (c for n in count(1) for c in str(n) )
def agen():
    s, g = "", bgen()
    while True:
        s += next(g); yield int(s)
print(list(islice(agen(), 20))) # Michael S. Branicky, Oct 25 2022

Crossrefs

Cf. A007908 (concatenate 1 through n), A033307.

Sequence in context: A035239 A344183 A057137 * A014824 A060555 A138957

Adjacent sequences: A252040 A252041 A252042 * A252044 A252045 A252046

Keyword

nonn,base

Author

José de Jesús Camacho Medina, Dec 15 2014

Extensions

Definition corrected by Zak Seidov, Jan 18 2015

Status

approved