1∈M; x∈M; (3x+1)∈M => 4∈M
4∈M; [tex]x^2[/tex]∈M; x∈M => 2∈M
2∈M; x∈M; (3x+1)∈M => 7∈M
7∈M; [tex]x^2[/tex]∈M; x∈M => [tex]\sqrt{7}[/tex]∈M
4∈M; x∈M; (3x+1)∈M => 13∈M
13∈M; x∈M; (3x+1)∈M => 40∈M
40∈M; x∈M; (3x+1)∈M => 121∈M
121∈M; [tex]x^2[/tex]∈M; x∈M => 11∈M
4∈M; x∈M; (3x+1)∈M => 13∈M