OFFSET
0,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..10000 (terms 0..1000 from Zak Seidov)
Norman Carey, Lambda Words: A Class of Rich Words Defined Over an Infinite Alphabet, arXiv preprint arXiv:1303.0888 [math.CO], 2013; Lambda Words: A Class of Rich Words Defined Over an Infinite Alphabet, J. Int. Seq. 16 (2013), Article 13.3.4.
FORMULA
a(n) ~ c * n^2, where c = log(2)/(2*log(3)) (A152747). - Amiram Eldar, Apr 07 2023
MATHEMATICA
c[0] = 1; c[n_] := 1 + Sum[Ceiling[j*Log[3, 2]], {j, n}]; Table[c[i], {i, 0, 60}] (* Norman Carey, Jun 13 2012 *)
PROG
(PARI) a(n)=my(t=1); 1+n+sum(k=1, n, logint(t*=2, 3)) \\ Ruud H.G. van Tol, Nov 25 2022
(Python)
from sympy import integer_log
def A022331(n):
m = 1<<n
return sum((m//3**i).bit_length() for i in range(integer_log(m, 3)[0]+1)) # Chai Wah Wu, Sep 16 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved