# 3

This number is a prime.

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

Jason Funk © 2002 |

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 R_{p}, where R_{p} denotes repunit with prime subscript p. [Gupta]

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