a(n) = 2^n - 1. (Sometimes called Mersenne numbers, although that name is usually reserved for A001348.)

A000225

a(n) = 2^n - 1. (Sometimes called Mersenne numbers, although that name is usually reserved for A001348.)

Terms

    a(0) =0a(1) =1a(2) =3a(3) =7a(4) =15a(5) =31a(6) =63a(7) =127a(8) =255a(9) =511a(10) =1023a(11) =2047a(12) =4095a(13) =8191a(14) =16383a(15) =32767a(16) =65535a(17) =131071a(18) =262143a(19) =524287a(20) =1048575a(21) =2097151a(22) =4194303a(23) =8388607a(24) =16777215a(25) =33554431a(26) =67108863a(27) =134217727a(28) =268435455a(29) =536870911

External references