A347690 Values of k such that (product of first k squarefree numbers) / (sum of first k squarefree numbers) is an integer.

1, 3, 8, 10, 12, 14, 16, 21, 22, 24, 30, 31, 34, 36, 37, 38, 39, 42, 43, 46, 51, 52, 55, 59, 60, 61, 62, 66, 67, 68, 72, 73, 75, 77, 78, 82, 83, 87, 91, 93, 96, 97, 98, 99, 101, 102, 105, 110, 115, 121, 124, 125, 129, 135, 136, 139, 140, 143, 145, 147, 151

Offset: 1

Author

N. J. A. Sloane, Sep 19 2021

Keywords

• nonn

Comments

a(n) is the number of terms in the numerator (or denominator) when A322609(n) is found.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005117, A111059, A173143, A322607, A322608.

Programs

Mathematica

Module[{nn=4000,sf},sf=Select[Range[nn],SquareFreeQ];Table[ If[ IntegerQ[ Times@@Take[sf,n]/Total[Take[sf,n]]],n,Nothing],{n,Length[sf]}]] (* Harvey P. Dale, Sep 19 2021 *)

Extensions

More terms from Harvey P. Dale, Sep 19 2021