OFFSET
1,4
COMMENTS
Write down all numbers of form 2^i*prime(j), j>0, i>=0, sort them, then extract i.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
f[n_] := Module[{e = IntegerExponent[n, 2]}, If[!CompositeQ[n / 2^e], e, Nothing]]; Array[f, 200] (* Amiram Eldar, Aug 24 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, May 06 2005
EXTENSIONS
a(1)-a(2) inserted by Amiram Eldar, Aug 24 2024
STATUS
approved