

A135974


a(n) = the smallest integer m > n such that d(m) > d(n), where d(n) = number of divisors of n.


0



2, 4, 4, 6, 6, 12, 8, 12, 10, 12, 12, 24, 14, 16, 16, 18, 18, 24, 20, 24, 24, 24, 24, 36, 26, 28, 28, 30, 30, 36, 32, 36, 36, 36, 36, 48, 38, 40, 40, 48, 42, 48, 44, 48, 48, 48, 48, 60, 50, 54, 52, 54, 54, 60, 56, 60, 60, 60, 60, 120, 62, 63, 64, 66, 66, 72, 68, 70, 70
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..69.


EXAMPLE

a(6)=12 because 6 has 4 divisors and the smallest integer > 6 which has more than 4 divisors is 12.


MAPLE

with(numtheory): a:=proc (n) local m: for m from n+1 while tau(m) <= tau(n) do end do: m end proc: seq(a(n), n=1..60); # Emeric Deutsch, Mar 21 2008


MATHEMATICA

a = {}; For[n = 1, n < 70, n++, i = n + 1; While[ ! DivisorSigma[0, i] > DivisorSigma[0, n], i++ ]; AppendTo[a, i]]; a (* Stefan Steinerberger, Mar 16 2008 *)


CROSSREFS

Cf. A000005, A112275.
Sequence in context: A226951 A251557 A231901 * A153494 A205404 A322372
Adjacent sequences: A135971 A135972 A135973 * A135975 A135976 A135977


KEYWORD

nonn


AUTHOR

Leroy Quet, Mar 02 2008


EXTENSIONS

More terms from Stefan Steinerberger, Mar 16 2008


STATUS

approved



