login
A363228
Exponent of 4 in 9^n - 1.
1
1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 2
OFFSET
1,2
COMMENTS
Not the same as A147648-without-zeros.
LINKS
FORMULA
a(n) = floor(A090739(n)/2).
a(n) = A244415(n) + 1.
a(n) = A235127(A024101(n)). - Michel Marcus, May 21 2023
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 5/3. - Amiram Eldar, Jul 13 2023
MATHEMATICA
a[n_] := IntegerExponent[2*n, 4] + 1; Array[a, 100] (* Amiram Eldar, May 22 2023 *)
PROG
(PARI) a(n) = valuation(2*n, 4) + 1;
(Python)
def A363228(n): return (~n&n-1).bit_length()+3>>1 # Chai Wah Wu, Jul 09 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ruud H.G. van Tol, May 21 2023
STATUS
approved