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A226445 Smallest k such that n is the n-th largest anti-divisor of k.

%I A226445 #13 Mar 12 2015 22:37:15
%S A226445 5,10,18,32,45,94,220,175,325,247,630,578,637,1012,2712,3867,4851,
%T A226445 2993,10230,2363,6435
%N A226445 Smallest k such that n is the n-th largest anti-divisor of k.
%e A226445 a(7) = 94 because the sorted anti-divisors of 94 are (63, 38, 27, 21, 10, 9, 7, 3, 2) and 7 is the 7th anti-divisor.
%p A226445 antidivisors := proc(n)
%p A226445     local a, k;
%p A226445     a := {} ;
%p A226445     for k from 2 to n-1 do
%p A226445         if abs((n mod k)- k/2) < 1 then
%p A226445             a := a union {k} ;
%p A226445         end if;
%p A226445     end do:
%p A226445     convert(a,list) ;
%p A226445 end proc:
%p A226445 A226445 := proc(n)
%p A226445     local k,adv;
%p A226445     for k from 3 do
%p A226445         adv := sort(antidivisors(k)) ;
%p A226445         if nops(adv) >= n then
%p A226445         if op(-n,adv) = n then
%p A226445             return k;
%p A226445         end if;
%p A226445         end if;
%p A226445     end do:
%p A226445 end proc: # _R. J. Mathar_, Jun 18 2013
%Y A226445 Cf. A066272, A130799.
%K A226445 nonn,less
%O A226445 2,1
%A A226445 _Juri-Stepan Gerasimov_, Jun 06 2013