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 A257796 #13 Jan 12 2019 02:27:31 %S A257796 1,16,9,16,9,9,0,16,9,1,0,9,16,9,9,16,48,9,16,16,9,0,9,9,9,9,9,9,0,9, %T A257796 16,9,0,0,16,9,16,0,9,16,9,9,0,0,9,16,0,48,0,9,9,9,16,9,0,0,9,9,0,9, %U A257796 16,9,9,16,0,0,16,9,9,0 %N A257796 Smallest value of the loop in which n ends, when iterating the map (A257588) which sends a number to absolute value of first digit squared minus second digit squared plus third digit squared etc. %C A257796 Six loops are possible. There are three loops of one. %C A257796 21.0% of the numbers end up as zero. %C A257796 Some numbers end up as a happy number (=1); density is 4.2%. %C A257796 Some numbers end up as 48; density is 4.8%. %C A257796 More numbers end up in a loop of two (16 and 35); density is 25.4%. %C A257796 Most numbers end up in a loop of five (9, 81, 63, 27, 45, 9); density is 44.6%. %H A257796 Pieter Post, <a href="/A257796/b257796.txt">Table of n, a(n) for n = 1..999</a> %e A257796 a(17)=48 because abs(1^2 - 7^2) = 48 => abs(4^2 - 8^2) = 48. %e A257796 a(34)=0 because abs(3^2 - 4^2) = 7 => 7^2 = 49 => abs(4^2 - 9^2) = 65 => abs(6^2 - 5^2) = 11 => abs(1^2 - 1^2) = 0. %Y A257796 Cf. A007770, A090425, A257588. %K A257796 nonn,base %O A257796 1,2 %A A257796 _Pieter Post_, May 09 2015