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 A099104 Characteristic function of badly sieved numbers (A066680). 6
 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(A066680(n)) = 1; A066683(n)=Sum(a(k):1<=k<=n); A066682(n)=a(n)*A066683(n). LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = Prod(if n>d^2 then 1 else 1-a(d): d d^2, 1, 1-a[d]], {d, Select[ Range[n-1], Mod[n, #] == 0 &] } ]; Table[ a[n], {n, 1, 105}](* Jean-François Alcover, Feb 15 2012, after formula *) PROG (PARI) A099104(n) = if(1==n, 0, my(m=1); fordiv(n, d, if((d=n), m *= (1-A099104(d)))); (m)); \\ Antti Karttunen, Jul 02 2018 CROSSREFS Cf. A066680, A066682, A066683, A099042. Sequence in context: A073070 A189687 A284653 * A066829 A194664 A285975 Adjacent sequences:  A099101 A099102 A099103 * A099105 A099106 A099107 KEYWORD nonn AUTHOR Reinhard Zumkeller, Sep 26 2004 STATUS approved

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Last modified October 18 20:11 EDT 2019. Contains 328197 sequences. (Running on oeis4.)