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 A066247 Characteristic function of composite numbers: 1 if n is composite else 0. 32
 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = signum(A066246(n)), where signum = A057427. For n > 1: a(n) = 1 - A010051(n) = A005171(n). a(n) = A057427(A086971(n)). - Reinhard Zumkeller, Dec 14 2012 LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 Index entries for characteristic functions Index entries for sequences computed from exponents in factorization of n FORMULA For n>1 a(n) = 1-floor(1/A001222(n)). - Enrique Pérez Herrero, Aug 08 2012 a(n) = A065855(n)-A065855(n-1) = 1-A000720(n)+A000720(n-1). - Chayim Lowen, Jul 23 2015 Dirichlet g.f.: Sum_{n>=1} a(n)/n^s = Zeta(s)-1-P(s), where P is prime zeta. - Enrique Pérez Herrero, Aug 08 2012 a(n) = 1 if A001222(n) > 1, 0 otherwise. - Antti Karttunen, Nov 20 2017 MATHEMATICA A066247[n_]:=1-Boole[PrimeQ[n]]-KroneckerDelta[n, 1] (* Enrique Pérez Herrero, Oct 13 2010 *) Table[Boole[CompositeQ[n]], {n, 1, 105}] (* Jean-François Alcover, Jan 25 2018 *) PROG (PARI) a(n)=!isprime(n)&&n>1 \\ Charles R Greathouse IV, Aug 21 2011 (Haskell) a066247 1 = 0 a066247 n = 1 - a010051 n -- Reinhard Zumkeller, Feb 04 2012 CROSSREFS Cf. A001222, A002808, A010051, A005171. Cf. A065855 (partial sums). Sequence in context: A106002 A341612 A252742 * A151774 A095792 A288381 Adjacent sequences: A066244 A066245 A066246 * A066248 A066249 A066250 KEYWORD nonn,easy,changed AUTHOR Reinhard Zumkeller, Dec 09 2001 STATUS approved

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Last modified February 22 05:23 EST 2024. Contains 370239 sequences. (Running on oeis4.)