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A081761
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Least number >n having same type of prime factorization, a(1)=1.
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10
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1, 3, 5, 9, 7, 10, 11, 27, 25, 14, 13, 18, 17, 15, 21, 81, 19, 20, 23, 28, 22, 26, 29, 40, 49, 33, 125, 44, 31, 42, 37, 243, 34, 35, 38, 100, 41, 39, 46, 54, 43, 66, 47, 45, 50, 51, 53, 80, 121, 52, 55, 63, 59, 56, 57, 88, 58, 62, 61, 84, 67, 65, 68, 729, 69, 70, 71, 75, 74, 78
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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sig[n_] := Sort @ FactorInteger[n][[;; , 2]]; a[1] = 1; a[n_] := Module[{sign = sig[n], k = n + 1}, While[sig[k] != sign, k++]; k]; Array[a, 70] (* Amiram Eldar, Dec 26 2020 *)
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PROG
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(PARI) a(n) = {if (n==1, 1, my(k=1, s = vecsort(factor(n)[, 2]~)); while (vecsort(factor(n+k)[, 2]~) != s, k++); n+k; )} \\ Michel Marcus, Nov 02 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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