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A226445 Smallest k such that n is the n-th largest anti-divisor of k. 1
5, 10, 18, 32, 45, 94, 220, 175, 325, 247, 630, 578, 637, 1012, 2712, 3867, 4851, 2993, 10230, 2363, 6435 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 22 17:14 EST 2020. Contains 332140 sequences. (Running on oeis4.)