Both are correct and can be used interchangeably. "Thought up" is more casual and informal, while "thought of" is more common in formal writing. Choose based on the tone and context of your writing.
Thought is the simple subject. Thought is an "idea".
Thought is already the past participle of "think".
The past of "think" is "thought."
Fought
The past participle is thought.
it was thought up when your mom fell in the ocean
Religions are not thought up by any one person.
who first thought up of knitting
When the Thought of You Catches Up with Me was created on 1994-08-29.
Akira, A Japanese person thought up Dragon ball z
me
the communication cycle was thought up by a man called Habermas luhmann
reconstructionism as a school of thought for curriculum design
Dreaming is uncontrolled thought during sleep. To dream up is to develop an idea, plan or thought while awake.
The Americans thought that they were teaming up
they thought they were magical
New Zealand did not 'sign up' for it. The country, as many others, thought it was their duty. Individuals did sign up. They thought it was their duty to do so