College Admissions Scandal Ringleader Rick Singer, Sentenced To 42 Months

The mastermind and architect behind the college admissions scandal is going to end up like Lori Loughlin and Felicity Huffman ... by spending time behind bars.

Rick Singer was sentenced to 42 months -- 3.5 years -- in federal prison for his role in the Varsity Blues scandal.

Remember ... the feds say Singer was the architect of a massive, decades-long fraudulent scheme to get high school students into elite colleges and universities across the country ... including the daughters of celebs like Lori and Felicity.

TMZ broke the story ... prosecutors were pushing for Singer to get 6 years behind bars, arguing he profited from the scheme more than anyone and therefore deserved a much longer sentence than the parents, college coaches and others received.

Singer's lawyers, meanwhile, asked for a maximum of 6 months in the big house.

It's worth noting ... more than 50 parents, coaches and associates of Singer's received sentences ranging from 30 months in prison to just probation. Lori was sentenced to 2 months behind bars, while Felicity got 2 weeks.

Singer was initially staring down a maximum sentence of 65 years behind bars ... but he ended up cooperating with the feds and was the key to convicting the parents and coaches. Prosecutors say Singer wore a wire at the government's direction to nail the targets, and also made hundreds of recorded calls.