id:A124268 - OEIS Search Results

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Primes indexed by 3-almost primes.

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19, 37, 61, 71, 103, 107, 113, 181, 193, 197, 229, 239, 307, 317, 337, 349, 379, 383, 397, 479, 521, 523, 557, 571, 601, 619, 641, 643, 683, 691, 733, 787, 853, 857, 883, 887, 971, 977, 1013, 1019, 1021, 1033, 1039, 1091, 1109, 1123, 1151, 1187, 1279 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`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.`
	FORMULA	`a(n) = prime(3almostprime(n)) = A000040(A014612(n)). {p such that p is prime and omega(primepi(p)) = 3} = {p such that p is in A000040 and A001222(A000720(p)) = 3}.`
	EXAMPLE	`a(1) = prime(3almostprime(1)) = prime(8) = 19.` `a(2) = prime(3almostprime(2)) = prime(12) = 37.` `a(3) = prime(3almostprime(3)) = prime(18) = 61.`
	CROSSREFS	`Cf. A000040, A014612, A122824, A124269, A124270.` `Sequence in context: A161705 A131600 A162471 this_sequence A154944 A039321 A043144` `Adjacent sequences: A124265 A124266 A124267 this_sequence A124269 A124270 A124271`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 23 2006`

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.

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