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A238337 Number of distinct squarefree numbers in row n of Pascal's triangle. 6
1, 1, 2, 2, 2, 3, 3, 4, 2, 1, 3, 6, 2, 5, 6, 7, 1, 3, 1, 4, 4, 5, 6, 12, 2, 2, 4, 1, 2, 6, 3, 6, 1, 2, 4, 4, 1, 4, 7, 6, 2, 6, 7, 13, 8, 4, 10, 21, 1, 1, 1, 2, 3, 9, 2, 3, 1, 3, 5, 11, 4, 13, 20, 4, 1, 2, 3, 4, 4, 8, 6, 9, 1, 4, 9, 2, 3, 7, 9, 17, 1, 1, 2, 3, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

T. D. Noe, Table of n, a(n) for n = 0..5000

FORMULA

a(n) + A064460(n) = A008619(n). - R. J. Mathar, Jan 18 2018

EXAMPLE

a(10)=3 because in row 10 of A007318 we observe the three squarefree numbers 1, 10 and 210.

MAPLE

A238337 := proc(n)

    local sqf ;

    sqf := {} ;

    for k from 0 to n do

        b := binomial(n, k) ;

        if b=1 or numtheory[issqrfree](b) then

            sqf := sqf union { b} ;

        end if;

    end do:

    nops(sqf) ;

end proc:

seq(A238337(n), n=0..10) ; # R. J. Mathar, Mar 06 2014

MATHEMATICA

Table[Length[Select[Binomial[n, Range[0, n/2]], SquareFreeQ[#] &]], {n, 0, 100}]

CROSSREFS

Cf. A048276 (number of squarefree numbers in the entire row), A238336.

Sequence in context: A139801 A132328 A064822 * A104484 A038809 A078342

Adjacent sequences:  A238334 A238335 A238336 * A238338 A238339 A238340

KEYWORD

nonn

AUTHOR

T. D. Noe, Mar 05 2014

STATUS

approved

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Last modified August 23 14:32 EDT 2019. Contains 326247 sequences. (Running on oeis4.)