Odd numbers that are one less than the square of a perfect power.

Terms

a(0) =15a(1) =63a(2) =255a(3) =1023a(4) =1295a(5) =4095a(6) =9999a(7) =16383a(8) =20735a(9) =38415a(10) =46655a(11) =65535a(12) =104975a(13) =159999a(14) =234255a(15) =262143a(16) =331775a(17) =456975a(18) =614655a(19) =809999a(20) =999999a(21) =1048575a(22) =1336335a(23) =1679615a(24) =2085135a(25) =2559999a(26) =2985983a(27) =3111695a(28) =3748095a(29) =4194303