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A116429
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The number of n-almost primes less than or equal to 9^n, starting with a(0)=1.
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8
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1, 4, 26, 181, 1095, 6416, 35285, 187929, 973404, 4934952, 24628655, 121375817, 592337729, 2868086641, 13798982719, 66043675287, 314715355788
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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MATHEMATICA
| AlmostPrimePi[k_Integer, n_] := Module[{a, i}, a[0] = 1; If[k == 1, PrimePi[n], Sum[PrimePi[n/Times @@ Prime[ Array[a, k - 1]]] - a[k - 1] + 1, Evaluate[ Sequence @@ Table[{a[i], a[i - 1], PrimePi[(n/Times @@ Prime[Array[a, i - 1]])^(1/(k - i + 1))]}, {i, k - 1}]] ]]]; Eric Weisstein (eww(AT)wolfram.com) Feb 07 2006
Table[ AlmostPrimePi[n, 9^n], {n, 13}]
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CROSSREFS
| Cf. A078840, A078841, A078842, A116432, A078843, A116426, A078844, A116427, A078845, A116428, A116429, A116430, A078846, A116431.
Sequence in context: A145840 A108082 A199490 * A084134 A098443 A052775
Adjacent sequences: A116426 A116427 A116428 * A116430 A116431 A116432
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KEYWORD
| more,nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 10 2006
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EXTENSIONS
| a(14)-a(16) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Oct 01 2010
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