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Search: id:A124270
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| 7, 19, 34, 41, 53, 44, 38, 103, 91, 73, 99, 75, 135, 142, 147, 118
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Primes indexed by 3-almost primes = A124268. 3-almost primes indexed by primes = A124269. 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.
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FORMULA
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a(n) = prime(3almostprime(n)) - 3almostprime(prime(n)) = A000040(A014612(n)) - A014612(A000040(n)).
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EXAMPLE
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a(1) = prime(3almostprime(1)) - 3almostprime(prime(1)) = prime(8) - 3almostprime(2) = 19 - 12 = 7.
a(2) = prime(3almostprime(2)) - 3almostprime(prime(2)) = prime(12) - 3almostprime(3) = 37 - 18 = 19.
a(3) = prime(3almostprime(3)) - 3almostprime(prime(3)) = prime(18) - 3almostprime(5) = 61 - 27 = 34.
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CROSSREFS
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Cf. A000040, A014612, A122824, A124269, A124270.
Sequence in context: A053591 A165333 A154878 this_sequence A068678 A069833 A031337
Adjacent sequences: A124267 A124268 A124269 this_sequence A124271 A124272 A124273
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 23 2006
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