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 A169805 #9 Apr 17 2022 13:09:22 %S A169805 0,2,4,6,8,10,12,14,16,18,2,4,6,8,10,12,14,16,18,20,4,6,8,10,12,14,16, %T A169805 18,20,22,6,8,10,12,14,16,18,20,22,24,8,10,12,14,16,18,20,22,24,26,10, %U A169805 12,14,16,18,20,22,24,26,28,12,14,16,18,20,22,24,26,28,30,14,16,18,20,22,24,26 %N A169805 Twice the sum of the digits of n. %C A169805 The only n such that a(n) = n are 0 and 18. %H A169805 Erich Friedman, <a href="https://erich-friedman.github.io/numbers.html">What's Special About This Number?</a> %F A169805 a(n) = 2*A007953(n). %t A169805 2*Total[IntegerDigits[#]]&/@Range[0,80] (* _Harvey P. Dale_, Apr 17 2022 *) %Y A169805 Cf. A007953. %K A169805 nonn,base %O A169805 0,2 %A A169805 _N. J. A. Sloane_, May 24 2010