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 A106794 Nonprimes of the form r(r(r(r(n)+1)+1)+1)+1, where A141468(n)=r(n)=n-th nonprime. 0
 1, 26, 34, 36, 45, 49, 51, 52, 56, 63, 65, 70, 76, 77, 78, 86, 88, 91, 93, 94, 95, 105, 116, 117, 118, 121, 123, 124, 125, 133, 135, 143, 146, 153, 154, 155, 160, 161, 162, 165, 170, 172, 175, 177, 185, 187, 188, 195, 201, 203, 205, 206, 207, 208, 209, 216, 217 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE If n=1, then r(r(r(r(1)+1)+1)+1)+1=r(r(r(0+1)+1)+1)+1=r(r(r(1)+1)+1)+1=r(r(0+1)+1)+1=r(r(1)+1)+1=r(0+1)+1=r(1)+1=0+1=1=a(1). If n=2, then r(r(r(r(2)+1)+1)+1)+1=r(r(r(1+1)+1)+1)+1=r(r(r(2)+1)+1)+1=r(r(1+1)+1)+1=r(r(2)+1)+1=r(1+1)+1=r(2)+1=1+1=2 (prime). If n=3, then r(r(r(r(3)+1)+1)+1)+1=r(r(r(4+1)+1)+1)+1=r(r(r(5)+1)+1)+1=r(r(8+1)+1)+1=r(r(9)+1)+1=r(14+1)+1=r(15)+1=22+1=23 (prime). If n=4, then r(r(r(r(4)+1)+1)+1)+1=r(r(r(6+1)+1)+1)+1=r(r(r(7)+1)+1)+1=r(r(10+1)+1)+1=r(r(11)+1)+1=r(16+1)+1=r(17)+1=25+1=26= a(2). If n=5, then r(r(r(r(5)+1)+1)+1)+1=r(r(r(8+1)+1)+1)+1=r(r(r(9)+1)+1)+1=r(r(14+1)+1)+1=r(r(15)+1)+1=r(22+1)+1=r(23)+1=33+1=34 =a(3). If n=6, then r(r(r(r(6)+1)+1)+1)+1=r(r(r(9+1)+1)+1)+1=r(r(r(10)+1)+1)+1=r(r(15+1)+1)+1=r(r(16)+1)+1=r(24+1)+1=r(25)+1 35+1=36=a(4). If n=7, then r(r(r(r(7)+1)+1)+1)+1=r(r(r(10+1)+1)+1)+1=r(r(r(11)+1)+1)+1=r(r(16+1)+1)+1=r(r(17)+1)+1=r(25+1)+1=r(26)+1 36+1=37 (prime). If n=8, then r(r(r(r(8)+1)+1)+1)+1=r(r(r(12+1)+1)+1)+1=r(r(r(13)+1)+1)+1=r(r(20+1)+1)+1=r(r(21)+1)+1=r(30+1)+1=r(31)+1=44+1=45 =a(5). If n=9, then r(r(r(r(9)+1)+1)+1)+1=r(r(r(14+1)+1)+1)+1=r(r(r(15)+1)+1)+1=r(r(22+1)+1)+1=r(r(23)+1)+1=r(33+1)+1=r(34)+1 48+1=49=a(6). If n=10, then r(r(r(r(10)+1)+1)+1)+1=r(r(r(15+1)+1)+1)+1=r(r(r(16)+1)+1)+1=r(r(24+1)+1)+1=r(r(25)+1)+1=r(35+1)+1=r(36)+1 50+1=51=a(7) If n=11, then r(r(r(r(11)+1)+1)+1)+1=r(r(r(16+1)+1)+1)+1=r(r(r(17)+1)+1)+1=r(r(25+1)+1)+1=r(r(26)+1)+1=r(36+1)+1=r(37)+1=51+1=52=a(8), etc. CROSSREFS Cf. A000040, A141468. Sequence in context: A048126 A080932 A129914 * A119481 A232668 A100393 Adjacent sequences:  A106791 A106792 A106793 * A106795 A106796 A106797 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Aug 25 2008 EXTENSIONS 91 and 123 inserted by R. J. Mathar, Sep 05 2008 STATUS approved

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Last modified July 23 03:00 EDT 2019. Contains 325230 sequences. (Running on oeis4.)