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Search: id:A116427
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| A116427 |
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The number of n-almost primes less than or equal to 6^n, starting with a(0)=1. |
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+0
8
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| 1, 3, 13, 50, 200, 726, 2613, 9061, 30779, 102637, 338230, 1102674, 3566001, 11455355, 36597558, 116395587, 368749900, 1164407829, 3666312894, 11515047829, 36085395700, 112857846859
(list; graph; listen)
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OFFSET
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0,2
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MATHEMATICA
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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, 6^n], {n, 21}]
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CROSSREFS
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Cf. A078840, A078841, A078842, A116432, A078843, A116426, A078844, A116427, A078845, A116428, A116429, A116430, A078846, A116431.
Sequence in context: A045908 A118589 A113237 this_sequence A008827 A026529 A101052
Adjacent sequences: A116424 A116425 A116426 this_sequence A116428 A116429 A116430
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KEYWORD
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more,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 10 2006
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