A243351 Difference between 2n and the n-th squarefree number: a(n) = 2n - A005117(n).

1, 2, 3, 3, 4, 5, 4, 5, 5, 6, 7, 7, 7, 7, 8, 9, 8, 7, 8, 9, 9, 10, 11, 11, 12, 13, 13, 14, 15, 14, 15, 13, 13, 13, 13, 14, 15, 15, 16, 15, 16, 17, 17, 18, 19, 19, 20, 19, 20, 21, 20, 21, 21, 22, 23, 23, 23, 23, 24, 25, 25, 23, 24, 25, 25, 26, 27, 27, 28, 29, 29, 30

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..10001

Formula

a(n) = 2n - A005117(n).

a(n) = n - A243348(n).

a(n) ~ c * n, where c = 2 - Pi^2/6 (A152416). - Amiram Eldar, Mar 04 2024

Mathematica

Module[{sf=Select[Range[150], SquareFreeQ]}, Table[2n-sf[[n]], {n, Length[ sf]}]] (* Harvey P. Dale, Jun 26 2021 *)

Crossrefs

Cf. A005117, A152416, A243348.

Sequence in context: A302920 A280386 A204979 * A071585 A328801 A106500

Adjacent sequences: A243348 A243349 A243350 * A243352 A243353 A243354

Keyword

nonn

Author

Antti Karttunen, Jun 04 2014

Status

approved