Bash script which generates n elements of the Fibonacci sequence, recursively

fib_recur.sh

#!/bin/bash

# source https://en.wikipedia.org/wiki/Fibonacci_number
# assuming F_1 = 1 and F_2 = 1 for seed values

# recursion function

function fib_recur_func(){
    local F_n F_1 F_2 # Avoid leaking to main scope
    F_n=$1
    
    # base case
    if ((F_n < 2))
    then
        ((base=F_n))
    # iterator
    else
        F_1=$(fib_recur_func "(($F_n - 1))")
        F_2=$(fib_recur_func "(($F_n - 2))")
        ((base=F_1+F_2))
    fi
    
    echo -n "$base "
    base=0
}

# Main

read -p "Enter Count of Fibonacci Terms: " F_count

# input checking
re='^[0-9]+$'
if ! [[ $F_count =~ $re ]] ; then
    echo "Not a valid integer, exiting..." >&2; exit 1
fi

# begin script
F_1=1
F_2=1

for i in `seq $F_1 $F_2 $F_count`
do 
    fib_recur_func "$i"
done

# carriage return / line feed cleanup
echo