A360617 Half the number of prime factors of n (counted with multiplicity, A001222), rounded up.

0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 3, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 3, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 1, 2, 2, 1, 2, 1, 3, 2, 1, 1, 2, 1, 1, 1

Offset

1,8

Links

Table of n, a(n) for n=1..87.

Example

The prime indices of 378 are {1,2,2,2,4}, so a(378) = ceiling(5/2) = 3.

Mathematica

Table[Ceiling[PrimeOmega[n]/2], {n, 100}]

Crossrefs

Positions of 0's and 1's are 1 and A037143.

Positions of first appearances are A081294.

Rounding down instead of up gives A360616.

A112798 lists prime indices, length A001222, sum A056239, median* A360005.

A360673 counts multisets by right sum (exclusive), inclusive A360671.

First for prime indices, second for partitions, third for prime factors:

- A360676 gives left sum (exclusive), counted by A360672, product A361200.

- A360677 gives right sum (exclusive), counted by A360675, product A361201.

- A360678 gives left sum (inclusive), counted by A360675, product A347043.

- A360679 gives right sum (inclusive), counted by A360672, product A347044.

Cf. A000040, A000302, A001248, A026424, A168645, A359912, A360006, A360457.

Sequence in context: A333915 A293234 A347441 * A102097 A361566 A354991

Adjacent sequences: A360614 A360615 A360616 * A360618 A360619 A360620

Keyword

nonn

Author

Gus Wiseman, Mar 08 2023

Status

approved