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 A139805 #9 Sep 16 2015 13:14:25
%S A139805 20,28,36,42,44,48,52,54,60,66,68,72,76,78,80,84,88,90,92,96,99,100,
%T A139805 102,104,108,110,112,114,116,117,120,124,126,130,132,136,138,140,144,
%U A139805 148,150,152,153,156,160,162,164,168,170,171,172,174,176,180,184,186,188
%N A139805 A number n is included if (product{k|n, k<=sqrt(n)} k) (= A072499(n)) does not divide n.
%e A139805 The divisors of 42 that are each <= sqrt(42) are 1,2,3,6. The product of these is 36. 36 does not divide 42, so 42 is in the sequence.
%p A139805 A072499 := proc(n) local a,k ; a := 1 ; for k in numtheory[divisors](n) do if k^2 <= n then a := a*k ; fi ; od: a ; end: isA139805 := proc(n) RETURN( n mod A072499(n) <> 0 ) end: for n from 1 to 300 do if isA139805(n) then printf("%d,",n) ; fi ; od: # _R. J. Mathar_, May 24 2008
%t A139805 a = {}; For[n = 1, n < 200, n++, If[Mod[n,Times @@ (Select[Divisors[n], ! # > Sqrt[n] &])] > 0, AppendTo[a, n]]]; a (* _Stefan Steinerberger_ *)
%Y A139805 Cf. A072499.
%K A139805 nonn
%O A139805 1,1
%A A139805 _Leroy Quet_, May 22 2008
%E A139805 More terms from _R. J. Mathar_ and _Stefan Steinerberger_, May 24 2008