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A120046 The 10^n-th 5-almost prime. 2
32, 176, 1272, 10374, 89896, 810220, 7475817 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..6.

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@Sqrt[(n/(Prime@i*Prime@j*Prime@k))]}];

FiveAlmostPrime[n_] := Block[{e = Floor[Log[2, n] +4], a, b}, a = 2^e; Do[b = 2^p; While[FourAlmostPrimePi[a] < n, a = a + b]; a = a - b/2, {p, e, 0, -1}]; a + b/2]; Do[ Print@FiveAlmostPrime[10^n], {n, 0, 13}]

CROSSREFS

Cf. A114453, A006988, A114125, A120044, A120045.

Sequence in context: A181209 A231299 A029534 * A303798 A305243 A304477

Adjacent sequences:  A120043 A120044 A120045 * A120047 A120048 A120049

KEYWORD

hard,more,nonn

AUTHOR

Robert G. Wilson v, Feb 15 2006

STATUS

approved

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Last modified March 18 22:10 EDT 2019. Contains 321305 sequences. (Running on oeis4.)