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A081547
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Smallest composite number which is 1 more than the product of n (not necessarily distinct) prime numbers.
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1
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4, 10, 9, 25, 33, 65, 129, 385, 513, 1025, 2049, 4097, 8193, 16385, 32769, 98305, 131073, 262145, 524289, 1048577, 2097153, 4194305, 8388609, 16777217, 33554433, 67108865, 134217729, 268435457, 536870913, 1073741825, 2147483649
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(2*n+1) = 2^(2*n+1)+1, n>0. - Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 02 2003
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FORMULA
| For n>2, a(n) = 2^n+1 unless this is a Fermat prime (A019434), in which case a(n) = 2^(n-1)*3+1 (which is divisible by 5). - Dean Hickerson (dean.hickerson(AT)yahoo.com), Apr 05 2003
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CROSSREFS
| Cf. A081545, A081546, A081548, A073919, A007583.
Sequence in context: A073722 A199805 A053248 * A111072 A189895 A180862
Adjacent sequences: A081544 A081545 A081546 * A081548 A081549 A081550
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 01 2003
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 02 2003
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