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A perfect power is an integer n which is expressible as for integers x and y and y > 1.

The perfect powers up to 10000 are

0, 1, 4, 8, 9, 14, 21, 23, 28, 30, 41, 54, 69, 84, X1, X5, X8, 100, 121, 144, 160, 169, 183, 194, 201, 230, 247, 261, 294, 309, 344, 368, 381, 400, 441, 484, 509, 554, 5X1, 630, 681, 6E4, 714, 769, 804, 861, 900, 92E, 961, X04, X69, E14, E81, 1000, 1030, 10X1, 1154, 1209, 1228, 1284, 1323, 1331, 1341, 1400, 1481, 1544, 1609, 1694, 1708, 1761, 1830, 1901, 1985, 1994, 1X69, 1E44, 1E53, 2021, 2100, 21X1, 2284, 2369, 2454, 2541, 2630, 2721, 2814, 2909, 2X04, 2X15, 2E01, 3000, 3101, 3204, 3309, 3414, 3460, 3521, 3630, 3741, 3854, 3969, 3X84, 3E77, 3EX1, 4100, 4221, 4344, 4469, 4594, 4600, 4701, 4768, 4830, 48X8, 4961, 4X94, 5009, 5144, 5281, 5400, 5439, 5541, 5684, 5809, 5954, 5XX1, 6030, 6181, 61E4, 6314, 6469, 6604, 6761, 6900, 6X61, 7004, 705E, 7169, 7314, 7481, 7630, 77X1, 7954, 7E09, 8000, 8084, 8241, 8400, 8581, 8744, 8909, 8X94, 9061, 9230, 9401, 9594, 9769, 9887, 9944, 9E21, X100, X208, X2X1, X484, X669, X854, XX41, E030, E221, E414, E483, E609, E804, EX01, 10000

There are no consecutive perfect powers except (0,1) and (8,9), this is the proven Catalan’s conjecture (the additional properties of (8,9): the numbers n ≤ 10 with terminate reciprocal are {1, 2, 3, 4, 6, 8, 9, 10}, and the divisors of 10 are {1, 2, 3, 4, 6, 10}, the difference of these two sets are 8 and 9 (of course, the second set is a subset of the first set), (8 is because it has more prime factors 2 than 10, and 9 is because it has more prime factors 3 than 10) (thus, the numbers of digits of the reciprocal of all these n except 8 and 9 are all 1, while the numbers of digits of the reciprocal of 8 and 9 are 2), besides, the product of 8 and 9 is 60, which is the smallest Achilles number, besides, the concatenation of 8 and 9 is 89, which is the smallest Ziesel number and the smallest integer such that the factorization of

over Q includes coefficients other than

(i.e. the 89th cyclotomic polynomial,

, is the first with coefficients other than

), besides, the repunit with length k (Rk) (where k = the concatenation of n and the unit (1), i.e. k = 10n+1) is prime for both n = 8 and n = 9, and not for any other n ≤ 1000, besides, the squares of 8 and 9 are the only two 2-digit automorphic numbers, besides, if we add zero (0, the additive identity) between 8 and 9, we get 809, the number ≤1000 whose Collatz sequence is longest, besides, 8 and 9 are the only two natural numbers n such that centered n-gonal numbers (the kth centered n-gonal number is n×Tk+1, where Tk is the kth triangular number) cannot be primes (8 is because all centered 8-gonal numbers are square numbers (4-gonal numbers), 9 is because all centered 9-gonal numbers are triangular numbers (3-gonal numbers) not equal to 3, but all square numbers and all triangular numbers not equal to 3 are not primes, (note that 8+4 (centered 8-gonal numbers and non-centered 4-gonal numbers) and 9+3 (centered 9-gonal numbers and non-centered 3-gonal numbers) are both 10), in fact, all polygonal numbers with rank > 2 are not primes, i.e. all primes p cannot be a polygonal number (except the trivial case, i.e. each p is the second p-gonal number)), assuming the Bunyakovsky conjecture is true. (i.e. 8 and 9 are the only two natural number n such that

is not irreducible) (Note that for n = 10, the centered 10-gonal numbers are exactly the star numbers)).