Search: id:A138758
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%I A138758
%S A138758 2,4,0,0,0,0,0,0,1,0,2,0,0,1,0,0,1,1,1,1,0,0,1,0,0,0,2,6,0,0,1,0,0,0,0,
%T A138758 1,1,0,2,3,0,0,0,0,0,4,0,1,2,4,0,1,0,0,0,0,0,0,2,0,0,0,0,0,1,0,0,0,0,3,
%U A138758 1,1,2,0,1,0,0,0,0,0,0,0,0,0,1,1,0,0,0,1,0,0,1,0,2,0,1,0,0,0,1,3,0,0,1
%N A138758 Index of A001203(n) (continued fraction for pi) in A000040 (primes), 
               or 0 if A001203(n) is not prime.
%F A138758 a(n) = A000720(A001203(n)) * A010051(A001203(n))
%e A138758 This sequence starts 2,4,0,0,... since the 1st and 2nd terms of the continued 
               fraction expansion of Pi, A001203 = (3, 7, 15, 1,...) are the 2nd 
               resp. 4th primes, while the next two terms are not primes.
%o A138758 (PARI) default(realprecision,1000); t=contfrac(Pi); vector(#t,i,isprime(t[i])*primepi(t[i]))
%Y A138758 Cf. A001203, A138757, A138759, A005042.
%Y A138758 Sequence in context: A139627 A166926 A028573 this_sequence A107501 A126732 
               A028586
%Y A138758 Adjacent sequences: A138755 A138756 A138757 this_sequence A138759 A138760 
               A138761
%K A138758 nonn
%O A138758 1,1
%A A138758 M. F. Hasler (www.univ-ag.fr/~mhasler), Mar 31 2008

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