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 A064923 #9 Jun 19 2018 05:15:30
%S A064923 2,3,6,5,10,7,14,16,24,11,22,13,26,39,52,17,34,19,38,57,76,23,46,69,
%T A064923 72,115,120,29,58,31,62,64,96,155,160,37,74,111,148,41,82,43,86,129,
%U A064923 172,47,94,141,144,235,240,53,106,159,162,265,270,59,118,61,122,183,244
%N A064923 a(n) = Min { k | A064920(k) = n }.
%C A064923 A064920(a(n)) = n. a(n) = n iff n is prime.
%H A064923 Harry J. Smith, <a href="/A064923/b064923.txt">Table of n, a(n) for n = 2..1000</a>
%o A064923 (PARI) gpf(n)= { local(f); f=factor(n)~; return(f[1, length(f)]) } { for (n=2, 1000, k=1; until (m==n, k++; g=gpf(k); m=k / g + g - 1); write("b064923.txt", n, " ", k) ) } \\ _Harry J. Smith_, Sep 29 2009
%Y A064923 Cf. A064920, A064924, A064919.
%K A064923 nonn
%O A064923 2,1
%A A064923 _Reinhard Zumkeller_, Oct 14 2001