how many percy jackson and the olympians books are there and does Percy's mother ever appear in the series?

Percy Jackson and the Olympians is a series of young adult novels written by Rick Riordan. The series consists of five main books, each exploring different adventures of the demigod hero, Percy Jackson. However, the depth of the series extends beyond these five books, as there are numerous short stories, comics, and other supplementary materials that expand on the world of Greek mythology and the adventures of Percy and his friends.

The five main books of Percy Jackson and the Olympians are:

The Lightning Thief - This is the first book where Percy discovers he is a demigod and sets off to face his destiny.
Poseidon’s Song - In this book, Percy, Annabeth, and Grover embark on a quest to find the lost gods and prevent Poseidon from being banished from Mount Olympus.
The Sea of Monsters - Percy, along with his friends, must navigate through the sea to rescue Clarisse and find the treasure of the Kraken.
The Titan’s Curse - Percy, Annabeth, and Thalia go on a dangerous journey to retrieve Zeus’ lightning bolt and prevent the Titans from rising again.
The Blood of Olympus - The final installment, Percy, Annabeth, and Jason must confront the last of the gods and the monsters left behind.

Each book in the series introduces new characters, expands on the mythology, and deepens the relationship between Percy and his companions. The books are not only thrilling adventures but also offer profound lessons about friendship, courage, and the importance of believing in oneself.

While Percy’s mother, Sally Jackson, does not appear in the main series, she plays a significant role in the character development and backstory. Her absence from the books serves to create a sense of mystery and adds layers to Percy’s character. In the spin-off graphic novel series, “The Lost Hero,” Sally appears briefly, providing insight into Percy’s past and her own struggles as a single parent.

In summary, Percy Jackson and the Olympians consists of five main books, but the universe of Greek mythology and the adventures of Percy and his friends extend far beyond these five volumes. Sally Jackson, though absent from the main series, remains an integral part of Percy’s narrative and background.