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Search: id:A158989
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| A158989 |
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Numbers n such that product of double factorials of the digits of n equals sigma(n). |
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+0
1
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| 1, 54, 62, 4190, 4920, 10538, 12376, 16065, 16732, 26345, 37236, 47026, 48323, 53480, 56712, 58520, 61209, 62337, 65163, 83720, 84135, 94520, 100980, 126238, 135266, 141078, 143726, 146910, 147354, 154238, 174217, 183505, 185334, 207328
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OFFSET
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1,2
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EXAMPLE
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sigma(444119)=4!!*4!!*4!!*1!!*1!!*9!!, so 444119 is in the sequence.
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MATHEMATICA
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Select[Range[210000], DivisorSigma[1, # ]==Apply[Times, IntegerDigits[ # ]!! ]&]
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CROSSREFS
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Cf. A137603, A158990, A158991, A158992.
Sequence in context: A095521 A095511 A095501 this_sequence A088489 A025331 A025323
Adjacent sequences: A158986 A158987 A158988 this_sequence A158990 A158991 A158992
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KEYWORD
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base,easy,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Jul 07 2009
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