A340928 Least image of A001222 applied to the prime indices of n.

0, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 3, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 2, 0, 1, 0, 4, 0, 1, 0, 1, 0, 1, 0, 3, 0, 1, 0, 1, 0, 1, 0, 1, 0, 3, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 1

Offset

1,7

Comments

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

Links

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

Example

The prime indices of 4277 are {4,6,15} with images {2,2,2}, so a(4277) = 2.
The prime indices of 8303 are {8,8,9} with images {3,3,2}, so a(8303) = 2.

Mathematica

Table[If[n==1, 0, Min@@PrimeOmega/@PrimePi/@First/@FactorInteger[n]], {n, 100}]

Crossrefs

Positions of 0's are A000079.

Positions of first appearances are A033844.

The version for maximum is A340691.

A003963 multiplies together the prime indices.

A026794 counts partitions by sum and minimum.

A056239 adds up the prime indices.

A061395 selects the greatest prime index.

A112798 lists the prime indices of each positive integer.

Cf. A001222, A004277, A039900, A062447, A302540, A303975, A324522, A340610.

Sequence in context: A133565 A239704 A168570 * A355742 A267860 A325488

Adjacent sequences: A340925 A340926 A340927 * A340929 A340930 A340931

Keyword

nonn

Author

Gus Wiseman, Jan 28 2021

Status

approved