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A011262
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In the prime factorization of n, increment odd powers and decrement even powers (multiplicative and self-inverse).
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5
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1, 4, 9, 2, 25, 36, 49, 16, 3, 100, 121, 18, 169, 196, 225, 8, 289, 12, 361, 50, 441, 484, 529, 144, 5, 676, 81, 98, 841, 900, 961, 64, 1089, 1156, 1225, 6, 1369, 1444, 1521, 400, 1681, 1764, 1849, 242, 75, 2116, 2209, 72, 7, 20, 2601, 338, 2809, 324, 3025, 784, 3249
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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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Multiplicative with f(p^k) = p^(k-1) if k even, p^(k+1) if k odd.
Sum_{k=1..n} a(k) ~ c * n^3, where c = (1/3) * Product_{p prime} ((p^5 + p^4 - p + 1)/(p^5 + p^4 + p^3 + p^2)) = 0.21311151701724196530... . - Amiram Eldar, Oct 13 2022
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MATHEMATICA
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f[n_, k_] := n^(If[EvenQ[k], k - 1, k + 1]); Table[Times @@ f @@@ FactorInteger[n], {n, 57}] (* Jayanta Basu, Aug 14 2013 *)
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PROG
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(PARI) a(n)=my(f=factor(n)); return(prod(i=1, #f[, 1], f[i, 1]^(f[i, 2]-(-1)^f[i, 2]))) \\ Paul Tek, Jun 01 2013
(Haskell)
a011262 n = product $ zipWith (^)
(a027748_row n) (map a103889 $ a124010_row n)
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CROSSREFS
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KEYWORD
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nonn,easy,mult
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AUTHOR
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STATUS
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approved
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