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 A291352 #8 Aug 27 2017 23:44:19 %S A291352 1,3,7,191,25983,2663063519,7160414743310596607, %T A291352 208229791652776621349215306687873023871, %U A291352 45218742589363955614633859184750699518167124046103786511727246869388335095775 %N A291352 Numerators of the Collatz parity generator fractions. %C A291352 a(n) is a numerator of a fraction of the form a(n)/(2^2^n + 1) whose expansion into a repeating binary string models the n-th parity in the Collatz orbit of an integer. %e A291352 a(1)=1 => f(1) = 1/3 => b(1) = 101010... %e A291352 a(2)=3 => f(2) = 3/5 => b(2) = 10011001... %e A291352 elements in b(2) determine the parity of elements at index 2 in the Collatz parity sequence of an integer. %Y A291352 Cf. A006666. %K A291352 nonn %O A291352 1,2 %A A291352 _John Laky_, Aug 22 2017