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Search: id:A072268
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| A072268 |
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a(0)=1; a(n+1)=1+f(a(n))^2, where f(x) is the largest prime factor of x (A006530). |
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7
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| 1, 2, 5, 26, 170, 290, 842, 177242, 160802, 2810, 78962, 9223370, 5033760602, 2935496262242, 2154284576409188208716642, 1379590379356276893461978662419832989306970202, 10320758390549056348725939119133160378521185060950774444682
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Is the sequence bounded?
Essentially the same as A031439; a(n) = A031439(n-1)^2 + 1. - Charles R Greathouse IV, May 08 2009
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EXAMPLE
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Given a(5)=290: a(6)=1+lpf(a(5))^2=1+lpf(290)^2=1+29^2=842.
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MAPLE
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with(numtheory): a[0]:=1: a[1]:=2: for n from 2 to 20 do b:=factorset(a[n-1]): a[n]:=1+op(nops(b), b)^2: od: seq(a[n], n=0..20); (Deutsch)
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CROSSREFS
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Cf. A031439.
Sequence in context: A045903 A090878 A120762 this_sequence A019014 A128595 A111195
Adjacent sequences: A072265 A072266 A072267 this_sequence A072269 A072270 A072271
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 08 2002
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 05 2006
a(16) corrected by T. D. Noe (noe(AT)sspectra.com), Nov 26 2007
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