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Search: id:A114426
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| 16, 384, 13824, 552960, 29859840, 1672151040, 100329062400, 8126654054400, 682638940569600, 60072226770124800, 5406500409311232000, 540650040931123200000, 56227604256836812800000
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OFFSET
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1,1
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COMMENT
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4-almost prime analogue of primorial (A002110). The semiprime analogue of primorial is A112141. Equivalent for product of what A086046 is for sum. Bigomega(a(n)) = the number of not necessarily distinct prime factors of a(n) = A001222(a(n)) = A008586(n) = 4*n.
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FORMULA
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a(n) = Prod[from i = 1 to n] A014613(i).
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EXAMPLE
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a(5) = 29859840 = 16 * 24 * 36 * 40 * 54 = the product of the first 5 values of the 4-almost primes = 2^13 * 3^6 * 5, which has 4*5 = 20 prime factors (with multiplicity).
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CROSSREFS
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Cf. A001222, A002110, A008585, A014613, A008586, A086046, A112141.
Sequence in context: A027403 A116166 A034976 this_sequence A051360 A071133 A035021
Adjacent sequences: A114423 A114424 A114425 this_sequence A114427 A114428 A114429
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 13 2006
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