This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A030530 #20 Feb 18 2024 01:31:27
%S A030530 0,1,2,2,3,3,4,4,4,5,5,5,6,6,6,7,7,7,8,8,8,8,9,9,9,9,10,10,10,10,11,
%T A030530 11,11,11,12,12,12,12,13,13,13,13,14,14,14,14,15,15,15,15,16,16,16,16,
%U A030530 16,17,17,17,17,17,18,18,18,18,18,19,19,19,19,19,20,20,20,20,20,21,21,21
%N A030530 n appears A070939(n) times.
%H A030530 Reinhard Zumkeller, <a href="/A030530/b030530.txt">Table of n, a(n) for n = 0..10000</a>
%F A030530 A030190(n) = T(a(n), A083652(a(n))-n-1), T as defined in A083651.
%F A030530 a(A083652(k)) = k+1.
%F A030530 Sum_{n>=1} (-1)^(n+1)/a(n) = Sum_{n>=1} (-1)^(n+1)/A053738(n) = 0.90457767... . - _Amiram Eldar_, Feb 18 2024
%t A030530 Join[{0},Table[Table[n,IntegerLength[n,2]],{n,30}]]//Flatten (* _Harvey P. Dale_, Oct 20 2016 *)
%o A030530 (Haskell)
%o A030530 import Data.List (unfoldr)
%o A030530 a030530 n = a030530_list !! (n-1)
%o A030530 a030530_list = 0 : concatMap (\n -> unfoldr
%o A030530 (\x -> if x == 0 then Nothing else Just (n, div x 2)) n) [1..]
%o A030530 -- _Reinhard Zumkeller_, Dec 05 2011
%Y A030530 Cf. A030190, A053738, A070939, A083651, A083652.
%K A030530 easy,nonn
%O A030530 0,3
%A A030530 _J. Lowell_