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 A280490 #6 Jan 10 2017 19:12:14 %S A280490 1,1,3,4,5,1,7,8,1,5,11,6,13,7,5,16,17,6,19,1,7,11,23,12,25,13,27,7, %T A280490 29,1,31,32,11,17,35,12,37,19,13,10,41,7,43,11,9,23,47,24,49,10,17,13, %U A280490 53,54,55,1,19,29,59,10,61,31,63,64,65,11,67,17,23,7,71,24,73,37,1,19,77,13,79,20,81,41,83,1,85,43,29,11,89,9,91,23,31,47,95,48,97 %N A280490 a(n) = n / A280491(n) = n / gcd(n,A122111(n)). %H A280490 Antti Karttunen, <a href="/A280490/b280490.txt">Table of n, a(n) for n = 1..8192</a> %F A280490 a(n) = n / A280491(n) = n / gcd(n,A122111(n)). %o A280490 (Scheme) (define (A280490 n) (/ n (A280491 n))) %Y A280490 Cf. A088902 (the positions of 1's). %Y A280490 Cf. A122111, A280491, also A278520, A280488. %K A280490 nonn %O A280490 1,3 %A A280490 _Antti Karttunen_, Jan 09 2017