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

2,1

Links

Table of n, a(n) for n=2..22.

Example

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.

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

Crossrefs

Cf. A066272, A130799.

Sequence in context: A025010 A299144 A058555 * A296552 A251928 A153370

Adjacent sequences: A226442 A226443 A226444 * A226446 A226447 A226448

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Jun 06 2013

Status

approved