A161660 a(1)=1; a(n) = largest multiple of {number of divisors of a(n-1)} that is <= n.

1, 2, 2, 4, 3, 6, 4, 6, 8, 8, 8, 12, 12, 12, 12, 12, 12, 18, 18, 18, 18, 18, 18, 24, 24, 24, 24, 24, 24, 24, 24, 32, 30, 32, 30, 32, 36, 36, 36, 36, 36, 36, 36, 36, 45, 42, 40, 48, 40, 48, 50, 48, 50, 54, 48, 50, 54, 56, 56, 56, 56, 56, 56, 64, 63, 66, 64, 63, 66, 64, 70, 72, 72

Offset

1,2

Links

Table of n, a(n) for n=1..73.

Example

a(18)=18 because a(17)=12 has 6 divisors and the largest multiple of 6 not exceeding 18 is 18. - Emeric Deutsch, Jun 27 2009

Maple

with(numtheory): a[1] := 1: for n from 2 to 80 do for j while j*tau(a[n-1]) <= n do end do: a[n] := (j-1)*tau(a[n-1]) end do: seq(a[n], n = 1 .. 80); # Emeric Deutsch, Jun 27 2009

Crossrefs

Cf. A161661.

Sequence in context: A302043 A060681 A202479 * A343327 A060766 A321015

Adjacent sequences: A161657 A161658 A161659 * A161661 A161662 A161663

Keyword

nonn

Author

Leroy Quet, Jun 15 2009

Extensions

Extended by Emeric Deutsch, Jun 27 2009

Status

approved