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Number of connected numbers (A029827) in the interval [2^(n-1)+1, 2^n].
1

%I #14 Oct 29 2020 21:58:21

%S 0,0,0,1,0,5,8,21,42,89,180,361,720,1438,2867,5696,11282,22392,44340,

%T 87887,174045,344719,682767,1352375,2678305,5305631,10510870,20824910,

%U 41264654,81776998,162083352,321295873

%N Number of connected numbers (A029827) in the interval [2^(n-1)+1, 2^n].

%e From the 64 numbers with ceiling(log_2(x)) = 7, the following 8 are composite connected numbers: 85, 95, 99, 111, 115, 117, 119, 123. Among the others 13 primes, 4 true prime powers and 39 split numbers can be found.

%Y Cf. A029827, A029837, A036378-A036390.

%K nonn,more

%O 1,6

%A _Labos Elemer_

%E a(21)-a(32) from _Sean A. Irvine_, Oct 29 2020