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%I #5 Jun 13 2016 07:13:38
%S 53,89,151,173,251,263,281,419,433,457,463,541,569,701,743,761,769,
%T 809,863,881,911,1097,1129,1193,1213,1249,1291,1373,1427,1439,1459,
%U 1481,1571,1583,1657,1783,1931,1949,1951,2017,2029,2087,2203,2213,2287,2297
%N Primes indexed by 4-almost primes.
%C 4-almost primes indexed by primes = A124283. prime(4almostprime(n)) - 4almostprime(prime(n)) = A124284. Primes indexed by 3-almost primes = A124268. 3-almost primes indexed by primes = A124269. prime(3almostprime(n)) - 3almostprime(prime(n)) = A124270. See also A106349 Primes indexed by semiprimes. See also A106350 Semiprimes indexed by primes. See also A122824 Prime(semiprime(n)) - semiprime(prime(n)). Commutator [A000040,A001358] at n.
%H Giovanni Resta, <a href="/A124282/b124282.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = prime(4almostprime(n)) = A000040(A014613(n)). {p such that p is prime and omega(primepi(p)) = 4} = {p such that p is in A000040 and A001222(A000720(p)) = 4}.
%e a(1) = prime(4almostprime(1)) = prime(16) = 53.
%e a(2) = prime(4almostprime(2)) = prime(24) = 89.
%e a(3) = prime(4almostprime(3)) = prime(36) = 151.
%Y Cf. A000040, A014613, A114414, A122824, A124269, A124270, A124283, A124284.
%K easy,nonn
%O 1,1
%A _Jonathan Vos Post_, Oct 24 2006
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