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A075109
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Odd perfect powers (1 together with numbers m^k, m odd, k >= 2).
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11
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1, 9, 25, 27, 49, 81, 121, 125, 169, 225, 243, 289, 343, 361, 441, 529, 625, 729, 841, 961, 1089, 1225, 1331, 1369, 1521, 1681, 1849, 2025, 2187, 2197, 2209, 2401, 2601, 2809, 3025, 3125, 3249, 3375, 3481, 3721, 3969, 4225, 4489, 4761, 4913, 5041, 5329, 5625
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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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Sum_{n>=1} 1/a(n) = 1 + Sum_{k>=2} mu(k)*(1-zeta(k)*(2^k-1)/2^k) = 1.2890375574... - Amiram Eldar, Dec 19 2020
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MAPLE
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q:= n-> n=1 or n::odd and igcd(seq(i[2], i=ifactors(n)[2]))>1:
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MATHEMATICA
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Take[Union[Flatten[Table[a^b, {a, 1, 99, 2}, {b, 2, 15}]]], 50] (* Alonso del Arte, Nov 22 2011 *)
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PROG
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(Haskell)
a075109 n = a075109_list !! (n-1)
(Magma) [1] cat [n : n in [3..6000 by 2] | IsPower(n) ]; // Vincenzo Librandi, Mar 31 2014
(PARI) isok(m) = (m==1) || ((m%2) && ispower(m)); \\ Michel Marcus, May 04 2022
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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