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A188794 a(n) is the smallest integer k >= 2 such that the number of divisors d>1 of n-k with k|(n-d) equals A188550(n). 5
2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 5, 2, 3, 4, 2, 2, 3, 2, 3, 2, 5, 4, 2, 2, 3, 4, 2, 2, 3, 2, 3, 2, 2, 3, 7, 2, 3, 4, 2, 2, 5, 2, 3, 2, 3, 4, 2, 2, 3, 4, 5, 2, 2, 4, 3, 2, 2, 2, 3, 2, 3, 4, 2, 6, 2, 2, 3, 2, 3, 4, 5, 2, 3, 4, 2, 2, 7, 2, 3, 4, 5, 6, 2, 2, 3, 4, 2, 2, 3, 8, 5, 2, 2, 3, 4, 2, 3, 2, 3, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

COMMENTS

a(n) <= floor(sqrt(n)) follows from the definition of A188550.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..20004

MAPLE

with(numtheory):

a:= proc(n) local h, i, k, m;

       m, i:= 0, 0;

       for k from 2 to floor(sqrt(n)) do

          h:= nops(select(x-> irem(x, k)=0,

              [seq (n-d, d=divisors(n-k) minus{1})]));

          if h>m then m, i:= h, k fi

       od; i

    end:

seq(a(n), n=4..120);  # Alois P. Heinz, Apr 10 2011

CROSSREFS

Cf. A188550, A188579.

Sequence in context: A046921 A262954 A262813 * A161966 A187188 A183027

Adjacent sequences:  A188791 A188792 A188793 * A188795 A188796 A188797

KEYWORD

nonn

AUTHOR

Vladimir Shevelev, Apr 10 2011

STATUS

approved

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Last modified April 3 22:30 EDT 2020. Contains 333207 sequences. (Running on oeis4.)