A124308 - OEIS

A124308

Primes indexed by 5-almost primes.

131, 223, 359, 409, 593, 613, 659, 953, 997, 1049, 1069, 1223, 1283, 1543, 1601, 1693, 1733, 1747, 1811, 1987, 2003, 2069, 2503, 2593, 2693, 2713, 2789, 2801, 2903, 3079, 3181, 3221, 3301, 3323, 3541, 3571, 3727, 4003, 4127, 4283 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	LINKS	`Table of n, a(n) for n=1..40.`
	FORMULA	`a(n) = prime(5almostprime(n)) = A000040(A014614(n)). {p such that p is prime and omega(primepi(p)) = 5} = {p such that p is in A000040 and A001222(A000720(p)) = 5}.`
	EXAMPLE	`a(1) = prime(5almostprime(1)) = prime(32 = 2^5) = 131.` `a(2) = prime(5almostprime(2)) = prime(48 = 2^4 * 3) = 223.` `a(3) = prime(5almostprime(3)) = prime(72 = 2^3 * 3^2) = 359.` `a(4) = prime(5almostprime(4)) = prime(80 = 2^4 * 5) = 409.`
	MATHEMATICA	`Prime[#]&/@Select[Range[600], PrimeOmega[#]==5&] (* Harvey P. Dale, Nov 20 2015 *)`
	CROSSREFS	Cf. A124309 5-almost primes indexed by primes. A124310 prime(5almostprime(n)) - 5almostprime(prime(n)). 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. `Cf. A000040, A014614, A114405, A114415, A122824, A124269, A124270, A124282-A124284, A124309, A124310.` `Sequence in context: A142068 A350574 A141920 * A059702 A142442 A288410` `Adjacent sequences: A124305 A124306 A124307 * A124309 A124310 A124311`
	KEYWORD	`easy,nonn,less`
	AUTHOR	`Jonathan Vos Post, Oct 25 2006`
	STATUS	`approved`