A075159 Run lengths in the binary expansion of n-1 gives the vector of exponents in prime factorization of a(n), with the least significant run corresponding to the exponent of the least prime, 2.

1, 2, 3, 4, 6, 5, 9, 8, 12, 15, 7, 10, 18, 25, 27, 16, 24, 45, 35, 30, 14, 11, 21, 20, 36, 75, 49, 50, 54, 125, 81, 32, 48, 135, 175, 90, 70, 77, 105, 60, 28, 33, 13, 22, 42, 55, 63, 40, 72, 225, 245, 150, 98, 121, 147, 100, 108, 375, 343, 250, 162, 625, 243, 64, 96, 405