3

This number is a prime.

Just showing those entries submitted by 'Gupta': (Click here to show all)

Jason Funk © 2002
+ The only triangular number which is prime. [Gupta]

+ The only Fermat number which is also a triangular number. [Gupta]

+ 3 is the only integer n such that n!+1 and n!-1 are both primes. [Gupta]

+ Only one rare number ending in 3 has ever been found, i.e., 8888070771864228883913. [Gupta]

+ The only number (curiously prime) whose subfactorial is also prime. [Gupta]

+ !3 + 1 is prime. Note that !3 represents subfactorial 3. [Gupta]

+ 1!*2!*3! ± 1 are twin primes. [Gupta]

+ π(3) = !3, where !3 denotes subfactorial 3. [Gupta]

+ The floor function of phi^e = 3, where phi is golden ratio. [Gupta]

+ Only prime p that divides Rp, where Rp denotes repunit with prime subscript p. [Gupta]

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