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A051844
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a(n) = LCM_{k=0..n} (2^k + 1).
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2
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2, 6, 30, 90, 1530, 16830, 218790, 9407970, 2417848290, 137817352530, 28252557268650, 19296496614487950, 4650455684091595950, 12700394473254148539450, 41619192688853844763777650, 13775952780010622616810402150, 902834617343556174437903325704550
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OFFSET
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0,1
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LINKS
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FORMULA
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a(n) = lcm(2, 3, 5, ..., 2^n + 1).
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EXAMPLE
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a(3) = lcm(2, 3, 5) = 30.
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MATHEMATICA
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Module[{nn=20, c}, c=Table[2^n+1, {n, 0, nn}]; Table[LCM@@Take[c, n], {n, nn}]] (* Harvey P. Dale, Aug 04 2017 *)
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PROG
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(PARI) a(n) = {ret = 1; for (k=0, n, ret = lcm(ret, 2^k+1)); return(ret); } \\ Michel Marcus, May 24 2013
(Python)
from math import lcm
from itertools import accumulate
def aupton(nn): return list(accumulate((2**k+1 for k in range(nn+1)), lcm))
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CROSSREFS
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KEYWORD
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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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