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A086684
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a(n) = n! - Sum_{i} p_i!^e_i, where n = Product_{i} (p_i^e_i).
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0
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1, 0, 0, 20, 0, 712, 0, 40312, 362844, 3628678, 0, 479001590, 0, 87178286158, 1307674367874, 20922789887984, 0, 6402373705727962, 0, 2432902008176639876, 51090942171709434954, 1124000727777567763198, 0, 620448401733239439359986
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OFFSET
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1,4
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COMMENTS
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a(p) = 0 iff p is prime.
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LINKS
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FORMULA
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EXAMPLE
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a(6) = 6! - 2! - 3! = 720 - 2 - 6 = 712.
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MATHEMATICA
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g[n_] := Plus @@ Flatten[Table[ # [[1]]! ^ # [[2]], {1}] & /@ FactorInteger[n]]; Table[n! - f[n], {n, 1, 24}]
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PROG
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(PARI) for(i=1, 20, f=factor(i); print1(", "i!-sum(j=1, length(f[, 1]), f[j, 1]!^f[j, 2])))
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CROSSREFS
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KEYWORD
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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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