

A082120


Smallest difference > 1 between d and n/d for any divisor d of n.


10



2, 3, 4, 5, 6, 2, 8, 3, 10, 4, 12, 5, 2, 6, 16, 3, 18, 8, 4, 9, 22, 2, 24, 11, 6, 3, 28, 7, 30, 4, 8, 15, 2, 5, 36, 17, 10, 3, 40, 11, 42, 7, 4, 21, 46, 2, 48, 5, 14, 9, 52, 3, 6, 10, 16, 27, 58, 4, 60, 29, 2, 12, 8, 5, 66, 13, 20, 3, 70, 6, 72, 35, 10, 15, 4, 7, 78, 2, 24, 39, 82, 5
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OFFSET

3,1


COMMENTS

a(p) = p1 for prime p.


LINKS

Robert Israel, Table of n, a(n) for n = 3..10000


MAPLE

F:= proc(n) local p;
p:= min(select(t > t  n/t > 1, numtheory:divisors(n)));
p  n/p
end proc:
map(F, [$3..100]); # Robert Israel, Aug 12 2015


MATHEMATICA

sd[n_]:=Min[Select[Abs[#n/#]&/@Divisors[n], #>1&]]; Array[sd, 90, 3] (* Harvey P. Dale, Sep 28 2013 *)


PROG

(PARI) for(n=3, 100, v=divisors(n); r=sqrt(n); t=0; for(k=1, length(v), if(v[k]>=r, t=k; break)); if(v[t]^2==n, u=t, u=t1); if(v[t]v[u]<2, u=u1; t=t+1); print1(v[t]v[u]", "))


CROSSREFS

Cf. A082119, A056737, A003681, A082121.
Sequence in context: A245342 A203580 A043266 * A104148 A286450 A245344
Adjacent sequences: A082117 A082118 A082119 * A082121 A082122 A082123


KEYWORD

nonn,easy


AUTHOR

Ralf Stephan, Apr 04 2003


STATUS

approved



