OFFSET
1,3
COMMENTS
For n=2^e0*3^e1*5^e2... the alternate (i.e. 2^0,2,4...) bit positions of a(n) give e0, the alternate *remaining* bit positions (i.e. 2^1,5,9...) give e1, the *remaining* alternates (i.e. 2^3,11,19...) give e2 and so on. (Any finite vector of nonnegative integers can be uniquely encoded this way.) Every nonnegative integer appears exactly once in this sequence-despite its outlandish behavior: the next term, a(29) is 2^511 (which has 153 digits), followed by a(30)=11...
Inverse of sequence A059900 considered as a permutation of the nonnegative integers. - Howard A. Landman, Sep 25 2001
LINKS
EXAMPLE
a(360)=a(2^3 * 3^2 * 5^1)=45 thus: ...0 0 0 0 0 0 1 1 -> 3 from 2^3 ...0 0 1 0 -> 2 from 3^2 ...0 1 -> 1 from 5^1 ...00000101101 == 45.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Marc LeBrun, Feb 06 2001
STATUS
approved