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 A164292 Binary sequence identifying the twin primes (characteristic function of twin primes: 1 if n is a twin prime else 0). 11
 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Similar to prime binary digit sequence A010051. In decimal notation A164292=0.1646823906345389353962381... See also A164293 (similar to prime decimal sequence A051006). a(A001097(n))=1; a(A001359(n))=1; a(A006512(n))=1. [From Reinhard Zumkeller, Mar 29 2010] LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 Index entries for characteristic functions [From Reinhard Zumkeller, Mar 29 2010] FORMULA a(n) = c(n) * ceiling(( c(n+2) + c(n-2) )/2), where c is the prime characteristic. - Wesley Ivan Hurt, Jan 31 2014 MATHEMATICA Table[(PrimePi[n] - PrimePi[n - 1]) * Ceiling[(PrimePi[n + 2] - PrimePi[n + 1] + PrimePi[n - 2] - PrimePi[n - 3])/2], {n, 100}] (* Wesley Ivan Hurt, Jan 31 2014 *) PROG (Haskell) a164292 1 = 0 a164292 2 = 0 a164292 n = signum (a010051' n * (a010051' (n - 2) + a010051' (n + 2))) -- Reinhard Zumkeller, Feb 03 2014 CROSSREFS Cf. A129950, A010051, A164293, A051006. a(n) = A057427(A010051(n)*(A010051(n-2)+A010051(n+2))), n>2. [From Reinhard Zumkeller, Mar 29 2010] Sequence in context: A327205 A219071 A072629 * A337802 A257531 A151763 Adjacent sequences:  A164289 A164290 A164291 * A164293 A164294 A164295 KEYWORD nonn AUTHOR Carlos Alves, Aug 12 2009 STATUS approved

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Last modified April 18 02:38 EDT 2021. Contains 343072 sequences. (Running on oeis4.)