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A344879
a(n) = A344875(n) / A344878(n), where A344875(n) is multiplicative with a(2^e) = 2^(1+e) - 1, and a(p^e) = p^e -1 for odd primes p, and A344878(n) gives the least common multiple of the same factors.
4
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 3, 2, 1, 1, 6, 1, 1, 4, 1, 1, 1, 1, 3, 2, 1, 1, 1, 2, 3, 2, 1, 1, 2, 1, 3, 2, 1, 4, 2, 1, 1, 2, 6, 1, 1, 1, 3, 2, 1, 2, 6, 1, 1, 1, 1, 1, 2, 4, 3, 2, 5, 1, 4, 6, 1, 2, 1, 2, 1, 1, 3, 2, 1, 1, 2, 1, 3, 4
OFFSET
1,14
LINKS
MATHEMATICA
f[2, e_] := 2^(e + 1) - 1; f[p_, e_] := p^e - 1; a[1] = 1; a[n_] := Times @@ (fct = f @@@ FactorInteger[n])/LCM @@ fct; Array[a, 100] (* Amiram Eldar, Jun 03 2021 *)
PROG
(PARI)
A344875(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^(f[2, i]+(2==f[1, i]))-1)); };
A344878(n) = if(1==n, n, my(f=factor(n)~); lcm(vector(#f, i, (f[1, i]^(f[2, i]+(2==f[1, i]))-1))));
A344879(n) = (A344875(n) / A344878(n));
(Python)
from math import prod, lcm
from sympy import factorint
def A344879(n): return prod(a := tuple(p**(e+int(p==2))-1 for p, e in factorint(n).items()))//lcm(*a) # Chai Wah Wu, Jun 15 2022
CROSSREFS
Sequence in context: A357477 A172083 A337199 * A090189 A227141 A284997
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 03 2021
STATUS
approved