A064460 Number of distinct nonsquarefree entries in n-th row of Pascal's triangle.

0, 0, 0, 0, 1, 0, 1, 0, 3, 4, 3, 0, 5, 2, 2, 1, 8, 6, 9, 6, 7, 6, 6, 0, 11, 11, 10, 13, 13, 9, 13, 10, 16, 15, 14, 14, 18, 15, 13, 14, 19, 15, 15, 9, 15, 19, 14, 3, 24, 24, 25, 24, 24, 18, 26, 25, 28, 26, 25, 19, 27, 18, 12, 28, 32, 31, 31, 30, 31, 27, 30, 27, 36

Offset

0,9

Links

T. D. Noe, Table of n, a(n) for n = 0..1000

Formula

a(n) + A238337(n) = A008619(n). - R. J. Mathar, Jan 18 2018

Example

a(13) = 2 because C(13,5) = 3^2*11*13 and C(13,6) = 2^2*3*11*13.

Mathematica

f[ n_ ] := (c = 0; k = 1; While[ k < n/2 + .5, If[ Union[ Transpose[ FactorInteger[ Binomial[ n, k ] ] ] [ [ 2 ] ] ] [ [ -1 ] ] > 1, c++ ]; k++ ]; c); Table[ f[ n ], {n, 0, 100} ]

Prog

(PARI) a(n) = sum(k=0, n\2, !issquarefree(binomial(n, k))); \\ Michel Marcus, Mar 05 2014

Crossrefs

Cf. A048277, A064461, A064462.

Sequence in context: A318840 A318830 A242803 * A108481 A367076 A078070

Adjacent sequences: A064457 A064458 A064459 * A064461 A064462 A064463

Keyword

easy,nonn

Author

Robert G. Wilson v, Oct 02 2001

Status

approved