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 A038178 #24 Sep 03 2023 11:08:47 %S A038178 0,1,2,3,4,5,6,7,8,9,81,512,2401 %N A038178 Numbers k such that k = (sum of digits of k)^(number of digits of k). %C A038178 To prove completeness, consider that k^m contains more than m digits for every k >= 10 and check 1 <= k <= 9 explicitly. - Ulrich Schimke (ulrschimke(AT)aol.com) %C A038178 Subset of A023106. - _R. J. Mathar_, Oct 20 2008 %e A038178 512 is in the sequence because (5 + 1 + 2)^3 = 512. %t A038178 Select[Range[2500],#==Total[IntegerDigits[#]]^IntegerLength[#]&] (* _Harvey P. Dale_, Oct 26 2011 *) %Y A038178 Cf. A007953, A055642, A023106. %K A038178 nonn,nice,fini,full,base %O A038178 1,3 %A A038178 _Felice Russo_