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 A282900 #20 Feb 16 2025 08:33:42
%S A282900 2,3,2,2,3,2,5,2,4,2,2,3,2,7,5,2,2,3,2,2,3,5,2,2,3,2,3,2,4,7,3,2,2,2,
%T A282900 2,3,11,2,3,2,2,2,7,2,5,3,2,4,3,2,13,3,2,5,2,2,2,2,2,3
%N A282900 Least non-infinitary divisor of A162643(n).
%C A282900 Let n=q_1*...*q_t, where q_i are distinct increasing terms of A050376. This representation is unique (for n=1 the product is empty). Every subproduct is an infinitary divisor of n. All numbers having at least one non-infinitary divisor form A162643.
%H A282900 Amiram Eldar, <a href="/A282900/b282900.txt">Table of n, a(n) for n = 1..10000</a>
%H A282900 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/InfinitaryDivisor.html">Infinitary Divisor</a>
%e A282900 For n=60=3*4*5, no subproduct is 2,6,10,30. They are all non-infinitary divisors of 60. Since 60=A162643(17) then a(17) = 2.
%t A282900 Map[First@ Complement[Divisors@ #, If[# == 1, {1}, Sort@ Flatten@ Outer[Times, Sequence @@ (FactorInteger[#] /. {p_, m_Integer} :> p^Select[Range[0, m], BitOr[m, #] == m &])]]] &, Select[Range@ 198, ! IntegerQ@ Log2@ DivisorSigma[0, #] &]] (* _Michael De Vlieger_, Feb 24 2017, after Paul Abbott at A077609 *)
%Y A282900 Cf. A000005, A036537, A037445, A050376, A162643.
%K A282900 nonn
%O A282900 1,1
%A A282900 _Vladimir Shevelev_, Feb 24 2017