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%I #12 Feb 01 2014 15:34:44
%S 2,3,4,5,6,7,8,9,10,11,12,13,15,16,17,18,19,20,22,23,24,26,27,28,29,
%T 30,31,34,35,37,38,40,41,42,44,45,47,48,49,51,52,53,54,57,60,61,62,63,
%U 64,65,67,69,71,72,73,74,75,76,79,82,83,84,85,89,90,93,94,95
%N Positions of primes in A007775 (numbers not divisible by 2, 3 or 5).
%C From _Antti Karttunen_, Feb 01 2014: (Start)
%C Positions of primes among natural numbers coprime to 30.
%C Term 1 is missing from the sequence, because A007775(1)=1 is not considered a prime, terms 2 - 13 are all present, and 14 is the next term missing from here, as A007775(14)=49 is the first composite in that sequence.
%C (End)
%H Antti Karttunen, <a href="/A236866/b236866.txt">Table of n, a(n) for n = 1..10000</a>
%o (Python)
%o import sympy
%o from sympy import isprime
%o i=0
%o for n in range(1000):
%o if n%2 and n%3 and n%5:
%o i+=1 # A007775(i)=n
%o if isprime(n): print str(i)+',',
%o (Scheme, with Antti Karttunen's IntSeq-library):
%o (define A236866 (MATCHING-POS 1 1 (lambda (n) (prime? (A007775 n)))))
%o ;; Where a slow version of A007775 can be defined for example like this:
%o (define A007775 (MATCHING-POS 1 1 (lambda (n) (= 1 (gcd n 30)))))
%o ;; from _Antti Karttunen_, Feb 01 2014
%Y Cf. A007775, A181709.
%K nonn,easy
%O 1,1
%A _Alex Ratushnyak_, Jan 31 2014
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