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Search: id:A134190
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| A134190 |
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a(1)=1. a(n) = n*a(n-1) if n*a(n-1) has a fewer number of divisors than n+a(n-1) does. a(n) = n+a(n-1) if n*a(n-1) has a greater or equal number of divisors than n+a(n-1) does. |
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+0
2
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| 1, 3, 9, 13, 65, 71, 497, 505, 514, 524, 535, 547, 7111, 7125, 106875, 106891, 1817147, 1817165, 34526135, 34526155, 34526176, 34526198, 34526221, 34526245, 34526270, 897683020, 897683047, 897683075, 897683104, 897683134, 897683165, 897683197
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OFFSET
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1,2
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EXAMPLE
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a(6)+7 = 71 + 7 = 78. a(6)*7 = 71 * 7 = 497. 78 has 8 divisors. 497 has 4 divisors. Since 497 has fewer divisors than 78, a(7) is therefore 497.
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MATHEMATICA
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a = {1}; For[n=2, n < 40, n++, If[Length[Divisors[n*a[[ -1]]]] < Length[Divisors[n+ a[[ -1]]]], AppendTo[a, n*a[[ -1]]], AppendTo[a, n + a[[ -1]]]]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Oct 26 2007
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CROSSREFS
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Cf. A134189.
Sequence in context: A018292 A089147 A094043 this_sequence A047905 A134904 A092476
Adjacent sequences: A134187 A134188 A134189 this_sequence A134191 A134192 A134193
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Oct 12 2007
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Oct 26 2007
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