For the Collatz (3x+1) iterations starting with the odd numbers k, a(n) is the smallest k such that the trajectory contains at least n successive odd numbers == 3 (mod 4).

A213215

For the Collatz (3x+1) iterations starting with the odd numbers k, a(n) is the smallest k such that the trajectory contains at least n successive odd numbers == 3 (mod 4).

Terms

    a(0) =1a(1) =3a(2) =7a(3) =15a(4) =27a(5) =27a(6) =127a(7) =255a(8) =511a(9) =1023a(10) =1819a(11) =4095a(12) =4255a(13) =16383a(14) =32767a(15) =65535a(16) =77671a(17) =262143a(18) =459759a(19) =1048575a(20) =2097151a(21) =4194303a(22) =7456539a(23) =16777215a(24) =33554431a(25) =67108863a(26) =125687199a(27) =125687199a(28) =125687199a(29) =1073741823

External references