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Search: id:A072944
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| A072944 |
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a(1)=2, a(n+1) = 2*a(n) - Phi(a(n)) where Phi is the Euler totient function. |
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+0
1
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| 2, 3, 4, 6, 10, 16, 24, 40, 64, 96, 160, 256, 384, 640, 1024, 1536, 2560, 4096, 6144, 10240, 16384, 24576, 40960, 65536, 98304, 163840, 262144, 393216, 655360, 1048576, 1572864, 2621440, 4194304, 6291456, 10485760, 16777216, 25165824
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OFFSET
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1,1
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COMMENT
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For any x=f(1) positive integer>1 there is an integer N(x) such that for any n>=N(x) f(n)/f(n-3)=4. N(2)=6 N(3)=5 N(4)=5 ... N(1479) =20. Conjecture: N(x) is asymptotic to C*Log(x) with C=0.3..... ( 3/10 < C < 4/10).
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FORMULA
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a(1)=2, a(2)=3, a(3)=4, a(4)=6, a(5)=10 and for n> 5 a(n) = 4*a(n-3)
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CROSSREFS
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Sequence in context: A098855 A143283 A104767 this_sequence A024722 A024965 A018142
Adjacent sequences: A072941 A072942 A072943 this_sequence A072945 A072946 A072947
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 14 2002
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