A172442 A sixth of the smallest integer for which the number of divisors is the n-th composite.

1, 2, 4, 6, 8, 10, 32, 24, 20, 30, 40, 96, 512, 60, 216, 2048, 150, 160, 120, 140, 1536, 32768, 864, 210, 131072, 6144, 280, 480, 2560, 600, 2097152, 420, 7776, 1080, 98304, 10240, 1050, 13824, 1120, 393216, 134217728, 840, 536870912, 2400, 1260, 55296, 7680, 163840, 6291456

Offset

1,2

Links

Table of n, a(n) for n=1..49.

Formula

a(n) = A005179(A002808(n))/6.

Example

The first composite is A002808(1)=4. The smallest integer with 4 divisors is A005179(4) = 6, which divided by 6 yields a(1)=1.

Crossrefs

Cf. A002808, A005179, A061286, A187678.

Sequence in context: A083490 A229363 A083498 * A061513 A134244 A195874

Adjacent sequences: A172439 A172440 A172441 * A172443 A172444 A172445

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Mar 12 2011

Status

approved