A013930 Sum of first a(n) squarefrees is squarefree.

1, 2, 3, 4, 5, 7, 9, 11, 13, 15, 17, 19, 20, 23, 25, 26, 27, 29, 32, 34, 37, 40, 41, 42, 43, 44, 46, 47, 49, 50, 51, 53, 54, 56, 58, 60, 61, 63, 64, 65, 69, 70, 71, 74, 76, 77, 79, 80, 81, 82, 83, 84, 86, 88, 89, 90, 92, 94, 95, 96, 98, 100, 102, 103, 104, 106, 107, 108, 110, 111

Offset: 1

Author

Henri Lifchitz

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A005117, A013931, A013932.

Programs

Mathematica

Position[Accumulate[Select[Range[200], SquareFreeQ]], ?SquareFreeQ, Heads -> False] // Flatten (* _Amiram Eldar, Mar 07 2021 *)

Extensions

More terms from David W. Wilson