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 A056009 #12 Dec 12 2017 00:51:03 %S A056009 1,1,7,1,521,1261,102943,1,38742049,99009901,23775972551,429960961, %T A056009 21633936185161,56406126018061,27368368148803711,1, %U A056009 45957792327018709121,121065871000912423309,98920982783015679456199 %N A056009 a(n) = (n^n + 1)/ (n^(2^a) + 1), where 2^a is the highest power of 2 dividing n. %H A056009 Michael De Vlieger, <a href="/A056009/b056009.txt">Table of n, a(n) for n = 1..388</a> %e A056009 The sixth term is (6^6 + 1)/ (6^(2^1) + 1) = 1261, since 2^1 is highest power of 2 dividing 6. %t A056009 Array[(#^# + 1)/(#^(2^IntegerExponent[#, 2]) + 1) &, 19] (* _Michael De Vlieger_, Dec 11 2017 *) %K A056009 easy,nonn %O A056009 1,3 %A A056009 _Leroy Quet_, Jul 24 2000