A101836 a(n) = 2^n - A143658(n).

0, 0, 1, 2, 5, 12, 25, 50, 99, 198, 400, 803, 1605, 3210, 6422, 12848, 25692, 51384, 102784, 205563, 411115, 822234, 1644470, 3288958, 6577915, 13155768, 26311537, 52623102, 105246259, 210492628, 420985102, 841970065, 1683940202, 3367880511, 6735761133, 13471522233

Offset: 0

Author

Robert G. Wilson v, Aug 31 2008

Keywords

• nonn

Comments

The number of integers not exceeding 2^n that are not squarefree.

Links

• Amiram Eldar, Table of n, a(n) for n = 0..64 (calculated from the b-file at A143658)

Crossrefs

Cf. A013929, A143658.

Programs

Mathematica

c = 0; k = 1; lst = {}; Do[ While[k <= 2^n, If[ !SquareFreeQ@ k, c++ ]; k++ ]; AppendTo[lst, c], {n, 0, 26}]; lst

Extensions

a(0) inserted and more terms added by Amiram Eldar, Feb 09 2021