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 A382461 #10 Mar 30 2025 09:53:19 %S A382461 1,2,4,8,79,5999,19999999,299999999999999, %T A382461 49999999999999999999999999999, %U A382461 899999999999999999999999999999999999999999999999999999999,799999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999 %N A382461 a(n) is the smallest number whose sum of digits is 2^n. %F A382461 a(n) = 10^(floor(2^n/9))*(1 + 2^n - 9*floor(2^n/9)) - 1. %F A382461 a(n) = A051885(2^n). %t A382461 a[n_]:=10^(Floor[2^n/9])(1+2^n-9Floor[2^n/9])-1; Array[a,11,0] %o A382461 (Python) %o A382461 def A382461(n): return (lambda x:(x[1]+1)*10**x[0]-1)(divmod(1<<n,9)) # _Chai Wah Wu_, Mar 29 2025 %Y A382461 Cf. A000079, A007953, A051885, A054750, A060712, A136308, A180083. %K A382461 nonn,base,easy %O A382461 0,2 %A A382461 _Stefano Spezia_, Mar 27 2025