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Number of 0's in first n terms of Van Eck's sequence (A181391).
4

%I #13 Sep 12 2019 15:01:56

%S 1,2,2,3,3,4,4,4,4,4,5,5,6,6,6,6,6,7,7,7,8,8,8,8,9,9,9,9,9,9,10,10,10,

%T 10,10,11,11,11,11,11,11,12,12,12,13,13,13,14,14,14,14,14,15,15,15,15,

%U 16,16,16,17,17,17,17,18,18,18,19,19,19,19,19,19,20,20,20,20

%N Number of 0's in first n terms of Van Eck's sequence (A181391).

%C Initially, seems to be about 0.136 times n. Maybe constant times n/log(n)? It would be nice to know more. - _N. J. A. Sloane_, Oct 10 2017

%C a(10^12) = 90689534032. - _Benjamin Chaffin_, Sep 11 2019

%H N. J. A. Sloane, <a href="/A171896/b171896.txt">Table of n, a(n) for n = 1..10000</a>

%H Benjamin Chaffin, <a href="/A171896/a171896.png">Plot of a(n)/n for the first 10^12 terms</a>

%Y Essentially A171895 + 1. First differences give A171894. Cf. A181391.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Oct 19 2010