A101836 - OEIS

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

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OFFSET

0,4

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)

MATHEMATICA

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

CROSSREFS

Cf. A013929, A143658.

Sequence in context: A166106 A067331 A116734 * A262667 A122439 A063807