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A164853
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a(n) = lcm(first n semiprimes).
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2
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4, 12, 36, 180, 1260, 1260, 1260, 13860, 69300, 900900, 900900, 15315300, 15315300, 290990700, 290990700, 6692786100, 46849502700, 46849502700, 46849502700, 46849502700, 1358635578300, 42117702927300, 42117702927300, 42117702927300
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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a(1) = 4, the first semiprime. a(2) = lcm(4,6) = 12. a(3) = lcm(4,6,9) = 36.
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MAPLE
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N:= 10^3: # to use semiprimes <= N
SP:= select(t -> numtheory:-bigomega(t)=2, [$4..N]):
A[1]:= SP[1]:
for n from 2 to N do
A[n]:= ilcm(A[n-1], SP[n])
od:
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MATHEMATICA
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With[{s=Select[Range[100], PrimeOmega[#]==2&]}, Table[LCM@@Take[s, n], {n, Length[s]}]] (* Harvey P. Dale, May 05 2015 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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