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

1,2

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

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 *)

Crossrefs

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

Sequence in context: A007284 A080892 A177091 * A246589 A327308 A350667

Adjacent sequences: A347687 A347688 A347689 * A347691 A347692 A347693

Keyword

nonn

Author

N. J. A. Sloane, Sep 19 2021

Extensions

More terms from Harvey P. Dale, Sep 19 2021

Status

approved