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!)
 A340676 If n is of the form s^(2^e), where s is a squarefree number, and e >= 0, then a(n) = 1+e, otherwise a(n) = 0. 4
 0, 1, 1, 2, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 1, 3, 1, 0, 1, 0, 1, 1, 1, 0, 2, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 2, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 3, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 2, 1, 1, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = A297109(A225546(n)). For n > 1, a(n) = A104117(A267116(n)). - Peter Munn, Feb 05 2021 MATHEMATICA a[1] = 0; a[n_] := If[Length[(u = Union[FactorInteger[n][[;; , 2]]])] == 1 && u[[1]] == 2^(e = IntegerExponent[u[[1]], 2]), e + 1, 0]; Array[a, 100] (* Amiram Eldar, Feb 10 2021 *) PROG (PARI) A001511(n) = 1+valuation(n, 2); A209229(n) = (n && !bitand(n, n-1)); A104117(n) = (A209229(n)*A001511(n)); A267116(n) = if(n>1, fold(bitor, factor(n)[, 2]), 0); A340676(n) = if(1==n, 0, A104117(A267116(n))); CROSSREFS Cf. A005117, A104117, A225546, A267116, A297109, A340673, A340675. Positions of zeros: {1} U A340681, of 1's: A005117 \ {1}, of 2's: A062503 \ {1}, of 3's: A113849. Positions of nonzero terms: A340682, of terms > 1: A340674. Sequence in context: A286935 A090340 A287364 * A117162 A277045 A146061 Adjacent sequences:  A340673 A340674 A340675 * A340677 A340678 A340679 KEYWORD nonn AUTHOR Antti Karttunen, Feb 01 2021 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 September 24 15:33 EDT 2021. Contains 347643 sequences. (Running on oeis4.)