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A271410
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LCM of exponents in binary expansion of 2n.
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11
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1, 1, 2, 2, 3, 3, 6, 6, 4, 4, 4, 4, 12, 12, 12, 12, 5, 5, 10, 10, 15, 15, 30, 30, 20, 20, 20, 20, 60, 60, 60, 60, 6, 6, 6, 6, 6, 6, 6, 6, 12, 12, 12, 12, 12, 12, 12, 12, 30, 30, 30, 30, 30, 30, 30, 30, 60, 60, 60, 60, 60, 60, 60, 60, 7, 7, 14, 14, 21, 21, 42
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OFFSET
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0,3
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LINKS
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EXAMPLE
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a(2) = lcm(2) = 2 because 2*2 = 2^2;
a(3) = lcm(1, 2) = 2 because 2*3 = 2^1 + 2^2;
a(7) = lcm(1, 2, 3) = 6 because 2*7 = 2^3 + 2^2 + 2^1.
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MATHEMATICA
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lcm[n_]:=Module[{idn2=IntegerDigits[n, 2]}, LCM@@Pick[Reverse[Range[ Length[ idn2]]], idn2, 1]]; Join[{1}, Array[lcm, 100]] (* Harvey P. Dale, Jan 24 2019 *)
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PROG
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(PARI) a(n) = my(ve = select(x->x==1, Vecrev(binary(2*n)), 1)); lcm(vector(#ve, k, ve[k]-1)); \\ Michel Marcus, Apr 12 2016
(Python)
from math import lcm
def A271410(n): return lcm(*(i for i, b in enumerate(bin(n)[:1:-1], 1) if b == '1')) # Chai Wah Wu, Dec 12 2022
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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