login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A080217 a(n) is the number of distinct values taken by binomial(n,j) mod j for j in [1..n]. 2
1, 2, 2, 2, 2, 4, 4, 4, 3, 4, 4, 7, 7, 6, 5, 7, 7, 7, 7, 9, 11, 12, 12, 12, 11, 11, 10, 11, 11, 12, 12, 12, 11, 12, 12, 13, 13, 13, 17, 18, 18, 15, 15, 18, 21, 17, 17, 19, 19, 18, 17, 16, 16, 20, 20, 23, 25, 23, 23, 26, 26, 24, 22, 24, 24, 27, 27, 27, 25, 28, 28, 30, 30, 32, 31, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = Card(Union{j=1..n} binomial(n,j) mod j).

EXAMPLE

n=14: {binomial(14,j) mod j, j=1..14} = {0,1,1,1,2,3,2,3,4,1,1,7,1,1} includes six distinct residues (0,1,2,3,4,7) so a(14) = 6.

MATHEMATICA

Table[Length[Union[Table[Mod[Binomial[n, j], j], {j, 1, n}]]], {n, 1, 256}]

PROG

(PARI) a(n) = #vecsort(vector(n, j, binomial(n, j) % j), , 8); \\ Michel Marcus, Jul 29 2017

CROSSREFS

Cf. A007318, A081370, A081371.

Sequence in context: A215244 A195427 A006643 * A157901 A327441 A335855

Adjacent sequences:  A080214 A080215 A080216 * A080218 A080219 A080220

KEYWORD

nonn

AUTHOR

Labos Elemer, Mar 21 2003

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 14 11:07 EDT 2021. Contains 342949 sequences. (Running on oeis4.)