login
A081372
a(n) is the number of j from 1 to n such that binomial(n,j) is divisible by j.
1
1, 1, 1, 2, 2, 1, 1, 2, 4, 3, 3, 3, 3, 1, 1, 3, 3, 5, 5, 4, 3, 1, 1, 2, 4, 2, 6, 7, 7, 2, 2, 8, 7, 6, 5, 6, 6, 4, 2, 4, 4, 2, 2, 2, 4, 2, 2, 4, 8, 12, 9, 8, 8, 12, 10, 12, 11, 8, 8, 6, 6, 3, 4, 14, 12, 9, 9, 9, 7, 4, 4, 7, 7, 6, 9, 11, 10, 4, 4, 6, 17, 15, 15, 11, 9, 6, 6, 9, 9, 6, 5, 6, 5, 2, 1, 4, 4, 9, 12
OFFSET
1,4
COMMENTS
a(n) is the number of 0's in row n of A081371.
LINKS
EXAMPLE
n=10: C(10,j) mod j, j=1..10, is {0,1,0,2,2,0,1,5,1,1} includes 3 zeros, so a(10)=3.
MAPLE
f:= n -> numboccur(0, map(j -> binomial(n, j) mod j, [$1..n])):
map(f, [$1..100]); # Robert Israel, Mar 19 2024
MATHEMATICA
Flatten[Table[Count[Table[Mod[Binomial[n, j], j], {j, 1, n}], 0], {n, 1, 256}], 1]
CROSSREFS
Sequence in context: A239473 A135229 A257543 * A101489 A104156 A070166
KEYWORD
nonn,look
AUTHOR
Labos Elemer, Mar 21 2003
EXTENSIONS
Definition edited by Robert Israel, Mar 19 2024
STATUS
approved