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1, 2, 3, 8, 5, 6, 7, 4, 27, 10, 11, 24, 13, 14, 15, 32, 17, 54, 19, 40, 21, 22, 23, 12, 125, 26, 9, 56, 29, 30, 31, 16, 33, 34, 35, 216, 37, 38, 39, 20, 41, 42, 43, 88, 135, 46, 47, 96, 343, 250, 51, 104, 53, 18, 55, 28, 57, 58, 59, 120, 61, 62, 189, 64, 65, 66, 67, 136, 69, 70, 71, 108, 73, 74, 375, 152, 77, 78, 79, 160, 243
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OFFSET
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1,2
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COMMENTS
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Self-inverse permutation of natural numbers obtained by mapping the exponent of each prime in the prime factorization of n through involution A193231.
Multiplicative with p^e -> p^A193231(e), p prime and e > 0.
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LINKS
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FORMULA
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EXAMPLE
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For n = 4 = 2^2, A193231(2) = 3, thus a(4) = 2^3 = 8.
For n = 9 = 3^2, A193231(2) = 3, thus a(9) = 3^3 = 27.
For n = 72 = 2^3 * 3^2, as A193231(2) = 3 and vice versa A193231(3) = 2, we have a(72) = 2^2 * 3^3 = 108. Note also how a(72) = a(8*9) = a(8) * a(9) = 4*27.
For n = 81 = 3^4, A193231(4) = 5, thus a(81) = 3^5 = 243.
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PROG
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(Scheme, two variants, both using memoization-macro definec)
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CROSSREFS
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KEYWORD
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nonn,mult
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AUTHOR
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STATUS
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approved
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