The phrase "a series of improper" is correct and usable in written English.
It can be used when referring to multiple instances or occurrences of something that is not proper or acceptable.
Example: "The report highlighted a series of improper practices that need to be addressed immediately."
Alternatives: "a number of inappropriate" or "multiple instances of improper".
The Missouri athletics department is tightening employee use of school-issued credit cards after an audit found a series of improper purchases, including bills for more than $7,600 from a Las Vegas strip club.
Then, in an even more unusual twist, Judge Van Wyke's decision was overruled by the nation's chief immigration judge, Michael J. Creppy, after what Judge Van Wyke and his supporters call a series of improper contacts between I.N.S. lawyers and Judge Creppy's office.
The Donald J. Trump Foundation made a series of improper purchases benefiting Trump personally, using funds donated by others.
The accounts of the Torricelli campaign's involvement in the anti-Zimmer mailing are the latest in a series of allegations of improper or illegal activities to emerge from the federal investigation.
The e-mail note, between partners in the Andersen Houston office, described a series of charges of improper accounting at Enron that had been raised in a phone call to the firm by a company employee, Sherron S. Watkins.
But it is impossible to disguise what was a dismal second quarter, with stocks pummeled by bleak earnings prospects, fears of terrorism and a series of revelations about improper accounting.
The investigation, conducted by the department's inspector general and its office of professional responsibility, is the fourth and last in a series of reports since last year detailing the use of improper political considerations in hiring decisions at the department.
Olympus, the medical imaging and digital camera maker, has lost half its stock market value this month since its ousted chief executive released internal documents that he said showed that the company made over $1 billion in improper payments over a series of acquisitions.
But Mr. Hewlett's suit, filed the next morning, on March 28, with its accusations that votes had been obtained by "improper means" and "a series of deceptions," struck the board as the act of someone who would be only a disruptive force.
That approval came in February after a series of hearings, in which civic groups accused the bank of improper lending practices.
Failure to display heat signs is an indication of improper functionality of signaling peptides to trigger on a series of behavioral changes, which can be detectable by breeders for timely insemination of females.
