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A345269
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a(n) = Sum_{d|n} (n/d)^(phi(n/d) - 1).
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0
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1, 2, 4, 6, 126, 11, 16808, 518, 59053, 1127, 2357947692, 1743, 1792160394038, 554633, 170859504, 268435974, 2862423051509815794, 1948628, 5480386857784802185940, 1280001131, 350277500559032, 1209627165485, 39471584120695485887249589624, 4586473679, 363797880709171295166015751
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OFFSET
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1,2
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COMMENTS
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If p is prime, a(p) = Sum_{d|p} (p/d)^(phi(p/d) - 1) = p^(p-2) + 1^(1-1) = p^(p-2) + 1.
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LINKS
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EXAMPLE
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a(10) = Sum_{d|10} (10/d)^(phi(10/d) - 1) = 10^(4-1) + 5^(4-1) + 2^(1-1) + 1^(1-1) = 1000 + 125 + 1 + 1 = 1127.
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MATHEMATICA
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Table[Sum[(n/k)^(EulerPhi[n/k^(1 - Ceiling[n/k] + Floor[n/k])] - 1) (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 30}]
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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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