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%I #16 Dec 06 2017 20:08:33
%S 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,
%U 0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0
%N Characteristic function of positive numbers that are primes ending in 9.
%H Antti Karttunen, <a href="/A185709/b185709.txt">Table of n, a(n) for n = 1..65539</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%t Table[If[PrimeQ[n]&&Mod[n,10]==9,1,0],{n,120}] (* _Harvey P. Dale_, Oct 22 2017 *)
%o (Scheme) (define (A185709 n) (if (= 9 (modulo n 10)) (A010051 n) 0)) ;; _Antti Karttunen_, Dec 06 2017
%Y Characteristic function of A030433.
%Y Cf. A010051.
%K base,nonn
%O 1
%A _N. J. A. Sloane_, Feb 10 2011
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