A048687 a(n) is the number of classes generated by function A001221 when applied to binomial coefficients.

1, 2, 2, 3, 3, 2, 3, 4, 4, 4, 5, 4, 4, 4, 4, 5, 6, 5, 6, 6, 5, 6, 7, 5, 6, 6, 8, 8, 8, 6, 7, 9, 7, 9, 9, 8, 8, 9, 10, 8, 10, 8, 9, 11, 8, 9, 10, 9, 10, 10, 10, 9, 11, 10, 12, 11, 12, 11, 13, 11, 12, 12, 12, 13, 13, 12, 14, 13, 14, 12, 14, 13, 13, 13, 13, 13, 12, 15, 15, 14, 16, 14, 16, 14

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Example

For n=9, A001221({binomial(9,k)})={0,1,2,3,3,3,3,2,1,0} includes 4 distinct values. Therefore, a(9) = 4.

Mathematica

Table[Length[Union[Table[PrimeNu[Binomial[n, k]], {k, 0, n}]]], {n, 1, 100}] (* G. C. Greubel, Apr 24 2017 *)

Prog

(PARI) a(n) = #Set(vector(n+1, k, omega(binomial(n, k-1)))); \\ Michel Marcus, May 14 2018

Crossrefs

Cf. A001221, A007947.

Sequence in context: A179751 A039645 A317993 * A308621 A308623 A115074

Adjacent sequences: A048684 A048685 A048686 * A048688 A048689 A048690

Keyword

nonn

Author

Labos Elemer

Status

approved