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 A098827 #15 Feb 22 2021 03:15:59 %S A098827 2,30,42,110,182,506,1406,2162,3422,3782,4290,4830,5402,6006,6806, %T A098827 11130,11342,12210,13110,16770,23870,24806,27390,27722,31862,33306, %U A098827 34410,34782,37442,37830,44310,49062,51302,56406,60762,64770,66822,68906 %N A098827 Squarefree oblong (pronic) numbers having an odd number of prime factors. %H A098827 Amiram Eldar, <a href="/A098827/b098827.txt">Table of n, a(n) for n = 1..10000</a> %e A098827 a(1)=2 is oblong and squarefree. %p A098827 ts_nsq_pronic:=proc(n) local i, ans; ans:=[ ]: for i from 1 to n do if (numtheory[mobius]( i*(i+1) ) = -1 ) then ans:=[ op(ans),i*(i+1)]: fi od; RETURN(ans) end: ts_nsq_pronic(500); %t A098827 Select[#*(# + 1) & /@ Range[250], MoebiusMu[#1] == -1 &] (* _Amiram Eldar_, Feb 22 2021 *) %Y A098827 Intersection of A002378 or A229882 with A030059. %Y A098827 Cf. A005117. %K A098827 nonn %O A098827 1,1 %A A098827 _Jani Melik_, Oct 09 2004