The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A193509 Number of odd divisors of Omega(n). 4
 0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 2, 2, 1, 2, 1, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,8 COMMENTS Omega(n) is the number of prime divisors of n counted with multiplicity, A001222 (also called bigomega(n)). Records are at 2^A053624(n). [Charles R Greathouse IV, Jul 29 2011] LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 EXAMPLE a(8) = 2 because Omega(8) = 3 and the 2 odd divisors are {1, 3}. MATHEMATICA f[n_] := Block[{d = Divisors[PrimeOmega[n]]}, Count[OddQ[d], True]]; Table[f[n], {n, 80}] PROG (PARI) a(n)=if(n==1, 0, my(k=bigomega(n)); numdiv(k>>valuation(k, 2))) \\ Charles R Greathouse IV, Jul 29 2011 CROSSREFS Cf. A001222. Sequence in context: A338274 A210960 A339095 * A331284 A331591 A003649 Adjacent sequences:  A193506 A193507 A193508 * A193510 A193511 A193512 KEYWORD nonn AUTHOR Michel Lagneau, Jul 29 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 11 12:38 EDT 2021. Contains 342886 sequences. (Running on oeis4.)