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 A272797 #9 May 07 2016 00:24:48 %S A272797 13,1,27,23,891,4795,125201,3253303 %N A272797 Least k for which A065413(k) = n, or 0 if no such k exists. %e A272797 a(3) = 23 because the first occurrence of 3 in A065413 is A065413(23) = 3. %p A272797 # given vector A of size N constructed as in A065413 %p A272797 M:= max(A): %p A272797 B:= Array(0..M): %p A272797 for i from 1 to N do %p A272797 if B[A[i]] = 0 then B[A[i]]:= i fi %p A272797 od: %p A272797 convert(B,list); # _Robert Israel_, May 06 2016 %Y A272797 Cf. A065413. %K A272797 nonn,more,base %O A272797 0,1 %A A272797 _Robert Israel_, May 06 2016