A175843 a(n) = (10^n)-th odd squarefree number.

1, 21, 241, 2463, 24671, 246745, 2467401, 24674017, 246740209, 2467401073, 24674011069, 246740110021, 2467401100859, 24674011004865, 246740110026451, 2467401100272455, 24674011002722867, 246740110027242491, 2467401100272345957

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Formula

a(n) ~ (pi/2)^2 * 10^n + O(10^(n/2)). This follows from the formula given in A056911: A056911(n) ~ n * (3/2) * zeta(2) + O(n^(1/2)) = n * (3/2) * (pi^2 / 6) + O(n^(1/2)). - M. F. Hasler

Crossrefs

Cf. A056911.

Sequence in context: A316426 A317428 A089937 * A198974 A271792 A177730

Adjacent sequences: A175840 A175841 A175842 * A175844 A175845 A175846

Keyword

nonn

Author

Zak Seidov, Sep 24 2010

Extensions

a(10)-a(18) from Max Alekseyev, Sep 24 2010

Edited by N. J. A. Sloane, Sep 24 2010

Status

approved