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A369165 - OEIS
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A369165 a(n) = A001222(A000688(n)). 4
0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,36
COMMENTS
First differs from A369164 at n = 36.
The sums of the first 10^k terms, for k = 1, 2, ..., are 3, 42, 450, 4592, 46185, 462402, 4625478, 46258861, 462599818, 4626029362, ... . From these values the asymptotic mean of this sequence, whose existence was proven by Ivić (1983) (see the Formula section), can be empirically evaluated by 0.4626... .
First differs from A056170 at n=128, 256, 384, 512, 640.... - R. J. Mathar, Jan 18 2024
REFERENCES
József Sándor, Dragoslav S. Mitrinovic, Borislav Crstici, Handbook of Number Theory I, Springer Science & Business Media, 2005, Chapter V, page 164.
LINKS
Aleksandar Ivić, On the number of abelian groups of a given order and on certain related multiplicative functions, Journal of Number Theory, Vol. 16, No. 1 (1983), pp. 119-137. See p. 131, eq. 4.5.
FORMULA
Sum_{k=1..n} a(k) = c * n + O(sqrt(n) * log(n)^3/log(log(n))), where c = Sum_{k>=1} d(k) * A001222(k) is a constant, d(k) is the asymptotic density of the set {m | A000688(m) = k} (e.g., d(1) = A059956, d(2) = A271971, d(3) appears in A048109) (Ivić, 1983).
MATHEMATICA
Table[PrimeOmega[FiniteAbelianGroupCount[n]], {n, 1, 100}]
PROG
(PARI) a(n) = bigomega(vecprod(apply(numbpart, factor(n)[, 2])));
CROSSREFS
Sequence in context: A101436 A366247 A374247 * A056170 A248395 A059483
KEYWORD
nonn,easy
AUTHOR
Amiram Eldar, Jan 15 2024
STATUS
approved

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Last modified August 1 00:10 EDT 2024. Contains 374809 sequences. (Running on oeis4.)