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 A337066 #21 Aug 13 2020 10:11:01 %S A337066 1,2,-1,-1,-1,3,-1,-1,-1,10,-1,7,-1,6,4,-1,-1,11,-1,15,12,14,-1,35,-1, %T A337066 18,-1,19,-1,31,-1,-1,8,22,5,39,-1,23,17,27,-1,30,-1,43,16,26,-1,67, %U A337066 -1,42,21,47,-1,71,9,34,24,51,-1,63,-1,46,20,-1,28,75,-1,55,25,50,-1,79,-1,54,36,38 %N A337066 a(n) is the smallest k such that A336957(k) = n, or -1 if n does not appear in A336957. %C A337066 There is a strong conjecture that numbers n >= 3 appear in A336957 if and only if they are divisible by at least two different primes. %H A337066 Scott R. Shannon, <a href="/A337066/b337066.txt">Table of n, a(n) for n = 1..20000</a> %Y A337066 Cf. A098550, A336957, A337007, A337008. %K A337066 sign %O A337066 1,2 %A A337066 _Scott R. Shannon_ and _N. J. A. Sloane_, Aug 13 2020