A217394 - OEIS

%I #38 May 16 2023 20:46:11

%S 2,20,21,22,23,24,25,26,27,28,29,200,201,202,203,204,205,206,207,208,

%T 209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,

%U 226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242

%N Numbers starting with 2.

%C The lower and upper asymptotic densities of this sequence are 1/18 and 10/27, respectively. - _Amiram Eldar_, Feb 27 2021

%H Jeremy Gardiner, <a href="/A217394/b217394.txt">Table of n, a(n) for n = 1..1111</a>

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.

%F a(n) = n + (17*10^floor(log_10(9*n-8))-8)/9. - _Alan Michael Gómez Calderón_, May 15 2023

%t Select[Range[300], IntegerDigits[#][[1]] == 2 &] (* _T. D. Noe_, Oct 02 2012 *)

%o (Python)

%o def agen():

%o   yield 2

%o   digits, adder = 1, 20

%o   while True:

%o     for i in range(10**digits): yield adder + i

%o     digits, adder = digits+1, adder*10

%o g = agen()

%o print([next(g) for i in range(54)]) # _Michael S. Branicky_, Feb 20 2021

%Y Cf. A006092, A011532.

%Y Subsequences include: A045708, A045726, A077327, A077678, A106412, A106422.

%Y Cf. A131835, A217395, A217397, A217398, A217399, A217400, A217401, A217402.

%K nonn,base,easy

%O 1,1

%A _Jeremy Gardiner_, Oct 02 2012