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

Offset: 1

Author

Antti Karttunen, Sep 13 2002

Keywords

• nonn

Comments

To make this a permutation of nonnegative integers, we subtract one from each run count except for the most significant run, e.g. a(12) = 10, as 12-1 = 11 = 1011 and 10 = 5^1 * 3^(1-1) * 2^(2-1).

Links

• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Inverse of A075160. a(n) = A075157(n-1)+1.