If your range is large enough, this recursion exceeds maximum call stack.

> sequenceSum(1,100000,1)
RangeError: Maximum call stack size exceeded
    at sequenceSum (repl:1:15)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)
    at sequenceSum (repl:5:18)

"Best Practices" - with recursion? mmm....