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A105882 Nonprimes of the form r(r(n)+1)+1, where A141468(n)=r(n)=n-th nonprime.

%I A105882 #6 Mar 30 2012 18:52:25
%S A105882 1,9,15,16,21,25,26,28,33,34,36,39,40,45,49,50,51,52,55,56,57,63,64,
%T A105882 65,69,70,76,77,78,81,86,87,88,91,93,94,95,100,105,106,111,112,115,
%U A105882 116,117,118,119,121,122,123,124,125,126,130,133,135,141,143,145,146,147,153
%N A105882 Nonprimes of the form r(r(n)+1)+1, where A141468(n)=r(n)=n-th nonprime.
%e A105882 If n=1, then r(r(1)+1)+1=r(0+1)+1=r(1)+1=0+1=1=a(1).
%e A105882 If n=2, then r(r(2)+1)+1=r(1+1)+1=r(2)+1=1+1=2 (prime).
%e A105882 If n=3, then r(r(3)+1)+1=r(4+1)+1=r(5)+1=8+1=9=a(2).
%e A105882 If n=4, then r(r(4)+1)+1=r(6+1)+1=r(7)+1=10+1=11 (prime).
%e A105882 If n=5, then r(r(5)+1)+1=r(8+1)+1=r(9)+1=14+1=15=a(3).
%e A105882 If n=6, then r(r(6)+1)+1=r(9+1)+1=r(10)+1=15+1=16=a(4).
%e A105882 If n=7, then r(r(7)+1)+1=r(10+1)+1=r(11)+1=16+1=17 (prime).
%e A105882 If n=8, then r(r(8)+1)+1=r(12+1)+1=r(13)+1=20+1+21=a(5).
%e A105882 If n=9, then r(r(9)+1)+1=r(14+1)+1=r(15)+1=22+1=23 (prime).
%e A105882 If n=10, then r(r(10)+1)+1=r(15+1)+1=r(16)+1=24+1=25=a(6), etc.
%Y A105882 Cf. A000040, A141468.
%K A105882 nonn
%O A105882 1,2
%A A105882 _Juri-Stepan Gerasimov_, Aug 25 2008
%E A105882 49 and 69 inserted by _R. J. Mathar_, Sep 05 2008