Use $(commands)
instead:
$ echo "hello1-$(echo hello2-$(echo hello3-$(echo hello4)))"
hello1-hello2-hello3-hello4
$(commands)
does the same thing as backticks, but you can nest them.
You may also be interested in Bash range expansions:
echo hello{1..10}
hello1 hello2 hello3 hello4 hello5 hello6 hello7 hello8 hello9 hello10
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