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 A114453 Number of 5-almost primes less than or equal to 10^n. 14
 0, 0, 4, 76, 963, 11185, 124465, 1349779, 14371023, 150982388, 1570678136, 16218372618, 166497674684, 1701439985694, 17323079621014 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS EXAMPLE There are 4 five-almost primes up to 100: 32,48,72&80. MATHEMATICA FiveAlmostPrimePi[n_] := Sum[ PrimePi[n/(Prime@i*Prime@j*Prime@k*Prime@l)] - l + 1, {i, PrimePi[n^(1/5)]}, {j, i, PrimePi[(n/Prime@i)^(1/4)]}, {k, j, PrimePi[(n/(Prime@i*Prime@j))^(1/3)]}, {l, k, PrimePi[(n/(Prime@i*Prime@j*Prime@k))^(1/2)]}]; Table[ FiveAlmostPrimePi[10^n], {n, 0, 12}] CROSSREFS Cf. A006880, A066265, A109251, A014613, A116382. Sequence in context: A045996 A190395 A240281 * A093184 A214814 A144210 Adjacent sequences:  A114450 A114451 A114452 * A114454 A114455 A114456 KEYWORD nonn AUTHOR Robert G. Wilson v, Feb 07 2006 EXTENSIONS a(13) and a(14) from Robert G. Wilson v, Jan 07 2007 STATUS approved

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Last modified September 29 07:08 EDT 2020. Contains 337425 sequences. (Running on oeis4.)