1330

+ The largest known natural number n such that n - 3k, with n > 3k, 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, 10n through 10n + 9, where n is a nonnegative integer, in which 10n + 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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