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A285057
a(n) = lcm(n, A001177(n)).
2
1, 6, 12, 12, 5, 12, 56, 24, 36, 30, 110, 12, 91, 168, 60, 48, 153, 36, 342, 60, 168, 330, 552, 24, 25, 546, 108, 168, 406, 60, 930, 96, 660, 306, 280, 36, 703, 342, 1092, 120, 820, 168, 1892, 660, 180, 552, 752, 48, 392, 150, 612, 1092, 1431, 108, 110, 168, 684, 1218, 3422, 60
OFFSET
1,2
LINKS
Paolo Leonetti, Carlo Sanna, On the greatest common divisor of n and the nth Fibonacci number, arXiv:1704.00151 [math.NT], 2017. See l(n) on page 2.
FORMULA
For p prime (except 5), a(p) = p*A001177(p). See Leonetti & Sanna link.
MATHEMATICA
z[n_]:=Block[{k=1}, While[Mod[Fibonacci[k], n]!=0, k ++]; k]; a[n_]:=LCM[n, z[n]]; Table[a[n], {n, 100}] (* Indranil Ghosh, Apr 09 2017 *)
PROG
(PARI) z(n) = {my(k = 1); while (fibonacci(k) % n, k++); k; }
a(n) = lcm(n, z(n));
(Python)
from sympy import fibonacci, lcm
def z(n):
k=1
while fibonacci(k)%n: k+=1
return k
def a(n): return lcm(n, z(n))
print([a(n) for n in range(1, 201)]) # Indranil Ghosh, Apr 09 2017
CROSSREFS
Cf. A001177.
Sequence in context: A102809 A060479 A028998 * A040030 A315567 A315568
KEYWORD
nonn
AUTHOR
Michel Marcus, Apr 09 2017
STATUS
approved