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%I #26 Jan 02 2023 12:30:50
%S 1,7,15,36,31,62,59,111,161,113,224,175,155,258,370,358,240,436,346,
%T 297,557,504,691,806,477,367,554,489,938,1743,786,959,725,1526,669,
%U 1215,1207,1022,1359,1286,958,1947,773,1206,1328,3078,2740,1165,915,1459,1787
%N Number of non-semiprimes among "preprimes" of the n-th kind (defined in comment in A247395).
%C One can prove that non-semiprimes we can find among preprimes of the n-th kind only with the smallest prime divisor 2,3,...,prime(n), where n=1 corresponds to A156759, n=2 corresponds to A247393, n=3 corresponds to A247394, etc. For example, for n=1, only among even numbers of A156759; for n=2 - only among even numbers and numbers with the smallest prime divisor 3 of A247393, etc. Thus, for every n>=1, among preprimes of the n-th kind almost all numbers are semiprimes.
%H Vladimir Shevelev, <a href="http://list.seqfan.eu/oldermail/seqfan/2014-September/013643.html">A classification of the positive integers over primes</a>
%Y Cf. A156759, A247393, A247394, A247395, A247396, A247509, A247510, A247511.
%K nonn
%O 1,2
%A _Vladimir Shevelev_, Sep 22 2014
%E More terms from _Peter J. C. Moses_, Sep 22 2014
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