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 A101040 If n has one or two prime-factors then 1 else 0. 5
 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(A033942(n))=0; for n>1: a(A037143(n))=1; a(A000040(n))=1; a(A001358(n))=1; A101041(n) = Sum(a(k): 1<=k<=n) + 1. LINKS FORMULA a(n) = A010051(n)+A064911(n) = 0^floor(A001222(n)/3)-0^(n-1). CROSSREFS Sequence in context: A106549 A075897 A135947 * A175629 A109720 A022932 Adjacent sequences:  A101037 A101038 A101039 * A101041 A101042 A101043 KEYWORD nonn AUTHOR Reinhard Zumkeller, Nov 28 2004 STATUS approved

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Last modified May 21 10:17 EDT 2013. Contains 225478 sequences.