Monitor

The Monitors are probably a hundred thousand year old A.I.s. The only Monitors that are known are 2401 Penitent Tangent and 343 Guilty Spark. Both Monitors control the Sentinels and Sentinel Majors. It is not known if 2401 Penitent Tangent can control the Sentinels and Sentinel Majors from the clutches of Gravemind, at the bottom of Delta Halo's Library. While 343 Guilty Spark glows blue, 2401 Penitent Tangent glows red. There's a question about 343 Guilty Spark. What was he guilty of??

Oracle
The Oracle is the another Covenant name for Halo maintenance robots, such as 343 Guilty Spark in Halo:Combat Evolved

Trivia

 * Also of interest is the fact that Penitent Tangent's number (2401) is $$7^4$$ while Guilty Spark's number (343) is $$7^3$$. The number seven is used frequently in Bungie games and mythology, possibly in Halo because of the suggested biblical references such as The Ark and The Flood, and the number's significance in some books of the Bible. Trivially, $$2+4+0+1=7$$.

When the numbers of each Monitor are examined, a pattern emerges: each seems to be seven raised to the power of the installation number minus one ($$7^{n-1}$$), or it could be that since the "oracles" are mechanical beings they operate most commonly using binary language in which case the exponentials are not a derived series manipulation, but rather they are simply the alpha numeric translations of binary code which starts from 0 not 1 thus the number "7" becomes 6 since the first integer value in the counting system is 0 not 1 (i.e. 0=1...6=7); regardless this would generate the following pattern,

Also, this may refer to the seven planes of heaven in order of one halo to another.

So, we can say that if n is the installation number, then 7n-1 is the monitor number of said installation.

Furthermore, one must note that there are seven unique letters in "Penitent Tangent". In earlier Bungie games, namely the Marathon series, names were often found to be sevens.

The seventh moniter number's first three digits are 117, the same as John 117.