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 A051282 2-adic valuation of A025487: largest k such that 2^k divides A025487(n), where A025487 gives products of primorials. 8
 0, 1, 2, 1, 3, 2, 4, 3, 1, 5, 2, 4, 2, 6, 3, 5, 3, 7, 4, 2, 6, 1, 3, 4, 8, 5, 3, 7, 2, 4, 5, 9, 6, 4, 8, 3, 5, 2, 6, 10, 3, 7, 2, 4, 5, 9, 4, 6, 3, 7, 11, 4, 8, 1, 3, 5, 6, 10, 5, 7, 4, 8, 12, 5, 9, 2, 4, 6, 3, 7, 11, 2, 4, 6, 8, 5, 3, 9, 5, 13, 6, 10, 3, 5, 7, 4, 8, 12, 3, 5, 7, 9, 2, 6, 4, 10, 6, 14, 7, 11, 4, 6, 8, 5, 9, 13, 4, 6, 8, 3, 10, 3, 7, 1, 5, 11, 7, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) can be used for resorting A025487 and sequences indexed by A025487, e.g., A050322, A050323, A050324 and A050325. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A007814(A025487(n)) = A051903(A025487(n)). - Matthew Vandermast, Jul 03 2012 EXAMPLE a(8) = 3 because A025487(8) = 24 and 2^3 divides 24. MATHEMATICA max = 40000; A025487 = {1}; lpe = {}; Do[ pe = Sort[ FactorInteger[n][[All, 2]]]; If[FreeQ[lpe, pe], AppendTo[lpe, pe]; AppendTo[A025487, n]], {n, 2, max}]; a[n_] := FactorInteger[ A025487[[n]] ][[1, 2]]; a[1] = 0; Table[a[n], {n, 1, Length[A025487]}] (* Jean-François Alcover, Jun 14 2012, after Robert G. Wilson v *) PROG (Haskell) a051282 = a007814 . a025487  -- Reinhard Zumkeller, Apr 06 2013 (PARI) isA025487(n)=my(k=valuation(n, 2), t); n>>=k; forprime(p=3, default(primelimit), t=valuation(n, p); if(t>k, return(0), k=t); if(k, n/=p^k, return(n==1))) [valuation(n, 2) | n <- [1..1000], isA025487(n)] \\ Or, for older versions: apply(n->valuation(n, 2), select(isA025487, [1..1000])) \\ Charles R Greathouse IV, Nov 07 2014 CROSSREFS A001055, A045778, A002033 and A050320. Sequence in context: A285120 A282744 A195310 * A274121 A052306 A322886 Adjacent sequences:  A051279 A051280 A051281 * A051283 A051284 A051285 KEYWORD nice,nonn AUTHOR EXTENSIONS More terms from Naohiro Nomoto, Mar 11 2001 STATUS approved

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Last modified August 6 18:25 EDT 2020. Contains 336256 sequences. (Running on oeis4.)