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12:13 AM
Had a weird problem I found:
Let $sd(x)$ be the sum of the digits of $x$, and define $a(x)$ as the sequence with $a(x)_0=x$ and $a(x)_{n+1}=a(x)_n+sd(a(x)_n)$.
Say two sequences $(b_n)_{n\in\mathbb N}$ and $(c_n)_{n\in\mathbb N}$ are asymptotically equivalent iff there exists $N\in\mathbb N$ s.t. for every $n\in\mathbb N$, if $n>N$ then $b_n=c_n$.
Are any of $a(1)$, $a(3)$, and $a(9)$ asymptotically equivalent?
For every $n\in\mathbb N$ other than $n=0$, is $a(n)$ asymptotically equivalent to at least one of $a(1)$, $a(3)$, and $a(9)$?
Tested them for a bunch of values and they seemed to be true but I've no idea about showing it
Another possibly interesting question is how far you have to go into $a(n)$ before it aligns with one of the other three, as it seems to always be very low.
 
OMG!! It's SBA!! Hello, @SimplyBeautifulArt! (Don't want to interrupt, though!) \o
Feel free to stop in at the Cafe and Tavern on the math.se, anytime, @SBA! Some homemade chocolate chip cookies are awaiting users there, now!
 
1:05 AM
@amWhy hello lol, just dropping stuff off into the chat :-)
 
@SimplyBeautifulArt How generous you are! How are you doing?
 
@amWhy gearing up for 5 classes starting tomorrow
 
@SimplyBeautifulArt Whoa! I hope you enjoyed a bit of a break?!
@SimplyBeautifulArt I'll make a point of stopping in to your chatroom more regularly; I'd love to hear more about your direction and plans. But very happy to see you keeping in touch with us, and contributing!
 
1:22 AM
@amWhy yeah, have been doing good
 
@SimplyBeautifulArt That's Greeeaaaat!
 
 
9 hours later…
10:37 AM
@SimplyBeautifulArt Curious recursion, though asymptotic equivalence is usually defined as $\lim\limits_{n\to\infty}\frac{b_n}{c_n}=1$ (for example Hazarika, 2015)
Maybe it's more that $d_n:=b_n-c_n$ is an integer Cauchy sequence $\to0$
 
10:55 AM
$a(1)$ is sequence A004207
$a(3)$ is sequence A016052
$a(9)$ is sequence A016096
See the comments in the links which verify your claims
 
 
2 hours later…
1:30 PM
@Mathphile Hi
 
Hello @Peter
 
Did you notice my conjecture and the surprising counterexample about $\Phi_n(n)$ ?
 
no
where can I see it
 
Just a moment
 
wow it does seem suprising
 
2:26 PM
@TheSimpliFire I meant to have them be eventually equivalent up to some constant shift btw
@TheSimpliFire interesting
 

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