A106613 Nonprimes of the form r(r(r(n)+1)+1)+1, where A141468(n)=r(n)=n-th nonprime.

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

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