51 (number)

51 (fifty-one) is the natural number 51 following 50 and preceding 52.

In mathematics

Fifty-one is the 14th discrete semiprime and the 5th in the {3.q} semiprime family having the prime factors (3.17). The aliquot sum of 51 is 21, itself a discrete semiprime. 51 is the 4th member of the 11-aliquot tree with the sequence (51, 21, 11, 1, 0).

51 is a pentagonal number as well as a centered pentagonal number (one of the few numbers to be both) and an 18-gonal number and a Perrin number. It is also the 6th Motzkin number, telling the number of ways to draw non-intersecting chords between any six points on a circle's boundary, no matter where the points may be located on the boundary.

Since the greatest prime factor of 51² + 1 = 2602 is 1301, which is substantially more than 51 twice, 51 is a Størmer number.

There are 51 different cyclic Gilbreath permutations on 10 elements, and therefore there are 51 different real periodic points of order 10 on the Mandelbrot set.

Since 51 is the product of the distinct Fermat primes 3 and 17, a regular polygon with 51 sides is constructible with compass and straightedge, the angle π/51 is constructible, and the number cos π/51 is expressible in terms of square roots.

Fifty-One

"Fifty-One" is the fourth episode of the fifth season of the American television drama series Breaking Bad, and the 50th overall episode of the series. Written by Sam Catlin and directed by Rian Johnson, it originally aired on AMC in the United States on August 5, 2012.

Plot

Walter (Bryan Cranston) and Walter Jr. (RJ Mitte) retrieve Walt's Pontiac Aztek from an auto repair shop. The mechanic (John Ashton) believes the car will last a long time, but when Walt puts on the hat he dons for his Heisenberg persona, his pride takes over: Walt sells the Aztek to the mechanic for $50, leases a new Chrysler 300 and later leases a new Dodge Challenger for Walt Jr.

At Madrigal's Houston branch, Lydia (Laura Fraser) receives a call from Mike (Jonathan Banks), who warns her that the police are about to arrive. She escorts Hank (Dean Norris), Gomez (Steven Michael Quezada), and other officers to the Madrigal warehouse and points out foreman Ron (Russ Dillen), who was supplying her with methylamine. Mike reassures Lydia that Ron will not talk, adding that she will have a new guy in the warehouse soon. Walter presents Skyler (Anna Gunn) with a stack of newly-earned drug money, saying they have to recoup the lost $600,000. After her suggestion of sending the kids to boarding school is struck down by Walter, he mentions that she should throw him a party for his 51st birthday.