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 A106613 Nonprimes of the form r(r(r(n)+1)+1)+1, where A141468(n)=r(n)=n-th nonprime. 0
 1, 15, 25, 26, 34, 36, 40, 45, 49, 51, 52, 55, 56, 57, 63, 65, 69, 70, 76, 77, 78, 81, 86, 87, 88, 91, 93, 94, 95, 105, 106, 112, 116, 117, 118, 119, 121, 123, 124, 125, 133, 135, 143, 145, 146, 153, 154, 155, 159, 160, 161, 162, 165, 169, 170, 172, 175, 177, 183, 185 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..60. EXAMPLE If n=1, then 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(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(3)+1)+1)+1=r(r(4+1)+1)+1=r(r(5)+1)+1=r(8+1)+1=r(9)+1=14+1=15=a(2). If n=4, then r(r(r(4)+1)+1)+1=r(r(6+1)+1)+1=r(r(7)+1)+1=r(10+1)+1=r(11)+1=16+1=17 (prime). If n=5, then 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=6, then r(r(r(6)+1)+1)+1=r(r(9+1)+1)+1=r(r(10)+1)+1=r(15+1)+1=r(16)+1=24+1=25=a(3). If n=7, then 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(4). If n=8, then r(r(r(8)+1)+1)+1=r(r(12+1)+1)+1=r(r(13)+1)+1=r(20+1)+1=r(21)+1=30+1=31 (prime). If n=9, then 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(5). If n=10, then 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(6), etc. CROSSREFS Cf. A000040, A141468. Sequence in context: A219880 A216379 A120746 * A192542 A325571 A366926 Adjacent sequences: A106610 A106611 A106612 * A106614 A106615 A106616 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Aug 25 2008 EXTENSIONS 28 removed, 93 added, 126 removed by R. J. Mathar, Sep 05 2008 STATUS approved

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Last modified March 2 02:30 EST 2024. Contains 370447 sequences. (Running on oeis4.)