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

1,2

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

Table of n, a(n) for n=1..66.

Index entries for sequences that are permutations of the natural numbers

Crossrefs

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

Sequence in context: A351412 A118315 A280577 * A362631 A374798 A191545

Adjacent sequences: A075156 A075157 A075158 * A075160 A075161 A075162

Keyword

nonn

Author

Antti Karttunen, Sep 13 2002

Status

approved