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 A064743 #8 May 18 2018 06:54:06 %S A064743 0,1,2,11,10,20,12,3,101,100,110,21,1001,1000,1010,13,4,102,10001, %T A064743 10000,10010,30,111,200,1100,1002,100001,100000,100010,22,5,1000001, %U A064743 1000000,1000010,1011,10000001,10000000,10000010,120,103,10002 %N A064743 A064413(n) written in base of primes, read from right to left, written as a string. %H A064743 J. C. Lagarias, E. M. Rains and N. J. A. Sloane, <a href="http://arXiv.org/abs/math.NT/0204011">The EKG sequence</a>, Exper. Math. 11 (2002), 437-446. %H A064743 <a href="/index/Ed#EKG">Index entries for sequences related to EKG sequence</a> %e A064743 A064413(12) = 18 = 3^2*2^1, so a(12) = 21. %Y A064743 Of course this "string" representation will not work once A064413 reaches 1024. See also A064744. %Y A064743 Cf. A064740, A064741, A064742, A064744. %K A064743 nonn %O A064743 1,3 %A A064743 _N. J. A. Sloane_, Oct 18 2001