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

5, 10, 18, 32, 45, 94, 220, 175, 325, 247, 630, 578, 637, 1012, 2712, 3867, 4851, 2993, 10230, 2363, 6435

Offset: 2

Author

Juri-Stepan Gerasimov, Jun 06 2013

Keywords

• nonn
• less

Examples

			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.
		

Crossrefs

Cf. A066272, A130799.

Programs

Maple

antidivisors := proc(n)
    local a, k;
    a := {} ;
    for k from 2 to n-1 do
        if abs((n mod k)- k/2) < 1 then
            a := a union {k} ;
        end if;
    end do:
    convert(a,list) ;
end proc:
A226445 := proc(n)
    local k,adv;
    for k from 3 do
        adv := sort(antidivisors(k)) ;
        if nops(adv) >= n then
        if op(-n,adv) = n then
            return k;
        end if;
        end if;
    end do:
end proc: # R. J. Mathar, Jun 18 2013