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A271410 LCM of exponents in binary expansion of 2n. 11
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
EXAMPLE
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.
MATHEMATICA
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 *)
PROG
(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
(PARI) a(n)=lcm(Vec(select(x->x, Vecrev(binary(n)), 1))) \\ Charles R Greathouse IV, 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
CROSSREFS
Sequence in context: A239962 A175175 A116417 * A196055 A145787 A096111
KEYWORD
nonn,base,look
AUTHOR
Peter Kagey, Apr 11 2016
STATUS
approved

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Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)