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 A067115 #6 Jul 09 2021 14:38:30
%S A067115 1,4,9,16,25,26,27,28,31,32,37,38,45,46,55,57,58,60,63,65,70,72,79,81,
%T A067115 90,93,94,97,100,103,108
%N A067115 Let N = 1357911131517192123252729... = concatenation of odd numbers. Then a(n) = sum of first n digits of N.
%H A067115 Harvey P. Dale, <a href="/A067115/b067115.txt">Table of n, a(n) for n = 1..1000</a>
%e A067115 a(6)= 1+3+5+7+9+1 = 26.
%t A067115 Module[{nn=20,codd},codd=Flatten[IntegerDigits/@(2Range[0,nn]+1)];Accumulate[ codd]] (* _Harvey P. Dale_, Jul 09 2021 *)
%Y A067115 Cf. A067112, A067113, A067114.
%K A067115 easy,nonn,base
%O A067115 1,2
%A A067115 _Amarnath Murthy_, Jan 08 2002