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# 1330

The largest known natural number n such that n -
3^{k}, with n >
3^{k}, is prime for all k > 0. [Capelle]

1330 is the only number m less than 7777777 such that |m - 3^k| is prime for k = 1, 2, . . . , 9. [Firoozbakht]

1330 begins the first decade of numbers, 10*n* through 10*n* + 9, where *n* is a nonnegative integer, in which 10*n* + 5 is divisible by 3 and there are no primes. [Litman]

There are 1330 sphenic numbers whose the prime factors are double-digit primes. May we call them “2-sphenic numbers”? [Loungrides]

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