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A072695
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a(n) = lcm(d(n^2),d(n)), where d(n) = A000005, the number of divisors of n.
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2
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1, 6, 6, 15, 6, 36, 6, 28, 15, 36, 6, 30, 6, 36, 36, 45, 6, 30, 6, 30, 36, 36, 6, 168, 15, 36, 28, 30, 6, 216, 6, 66, 36, 36, 36, 225, 6, 36, 36, 168, 6, 216, 6, 30, 30, 36, 6, 270, 15, 30, 36, 30, 6, 168, 36, 168, 36, 36, 6, 180, 6, 36, 30, 91, 36, 216, 6, 30, 36, 216, 6, 420
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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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If n is squarefree product of k distinct primes, then a(n) = 6^k.
If n = p^2, then a(n) = 15, etc.
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MATHEMATICA
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Table[LCM[DivisorSigma[0, n], DivisorSigma[0, n^2]], {n, 80}] (* Harvey P. Dale, Dec 26 2018 *)
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PROG
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(PARI) a(n) = {my(e = factor(n)[, 2]); lcm(vecprod(apply(x -> 2*x+1, e)), vecprod(apply(x -> x+1, e))); } \\ Amiram Eldar, Dec 02 2023
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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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STATUS
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approved
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