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 A077491 #9 Sep 15 2020 20:48:22 %S A077491 5,1,6,2,7,3,8,4,9,14,19,24,29,34,39,44,49,99,149,199,249,299,349,399, %T A077491 449,499,999,1499,1999,2499,2999,3499,3999,4499,4999,9999,14999,19999, %U A077491 24999,29999,34999,39999,44999,49999,99999,149999,199999,249999,299999 %N A077491 a(n) = smallest k such that 2k has digit sum = n. %H A077491 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,10,-10). %F A077491 a(n) = A069532(n)/2. %Y A077491 Cf. A069532, A069534. %K A077491 base,nonn,easy %O A077491 1,1 %A A077491 _Amarnath Murthy_, Nov 07 2002 %E A077491 More terms from _Ray Chandler_, Jul 28 2003