The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A124309 5-almost primes indexed by primes. 5
 48, 72, 108, 120, 180, 208, 270, 280, 368, 420, 450, 520, 592, 612, 660, 700, 760, 828, 920, 952, 976, 1032, 1064, 1128, 1242, 1288, 1323, 1372, 1380, 1428, 1575, 1624, 1674, 1700, 1752, 1768, 1880, 1976, 2028, 2096, 2178, 2196, 2312, 2328, 2384, 2394, 2475 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 FORMULA a(n) = 5almostprime(prime(n)) = A014614(A000040(n)). EXAMPLE a(1) = 5almostprime(prime(1)) = 5almostprime(2) = 48 = 2^4 * 3. a(2) = 5almostprime(prime(2)) = 5almostprime(3) = 72 = 2^3 * 3^2. a(3) = 5almostprime(prime(3)) = 5almostprime(5) = 108 = 2^2 * 3^3. PROG (PARI) list(lim)=my(v=List(), u=v); forprime(p=2, lim\16, forprime(q=2, min(lim\(8*p), p), forprime(r=2, min(lim\(4*p*q), q), forprime(s=2, min(lim\(2*p*q*r), r), forprime(t=2, min(lim\(p*q*r*s), s), listput(v, p*q*r*s*t)))))); v=Set(v); forprime(p=2, #v, listput(u, v[p])); v=0; Vec(u) \\ Charles R Greathouse IV, Feb 10 2017 CROSSREFS Cf. A124308 Primes indexed by 5-almost 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, A124282-A124284, A124309. Sequence in context: A043937 A173042 A309933 * A112058 A033821 A334899 Adjacent sequences:  A124306 A124307 A124308 * A124310 A124311 A124312 KEYWORD easy,nonn,less AUTHOR Jonathan Vos Post, Oct 25 2006 EXTENSIONS a(16)-a(47) from Giovanni Resta, Jun 13 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 25 09:40 EDT 2021. Contains 347654 sequences. (Running on oeis4.)