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A164073
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a(n) = 2*a(n-2) for n > 2; a(1) = 1, a(2) = 3.
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2
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1, 3, 2, 6, 4, 12, 8, 24, 16, 48, 32, 96, 64, 192, 128, 384, 256, 768, 512, 1536, 1024, 3072, 2048, 6144, 4096, 12288, 8192, 24576, 16384, 49152, 32768, 98304, 65536, 196608, 131072, 393216, 262144, 786432, 524288, 1572864, 1048576, 3145728
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Interleaving of A000079 and A007283.
Apparently equal to A074323 without initial 1. Also 1 followed by A162255.
Binomial transform is A048654. Second binomial transform is A111567. Third binomial transform is A081179 without initial 0. Fourth binomial transform is A164072. Fifth binomial transform is A164031.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..2000
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FORMULA
| a(n) = (5+(-1)^n)*2^(1/4*(2*n-1+(-1)^n))/4.
G.f.: x*(1+3*x)/(1-2*x^2).
a(n)=A072946(n-2), n>2. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 17 2009]
a(n+3) = a(n+2)*a(n+1)/a(n). [Reinhard Zumkeller, Mar 04 2011]
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PROG
| (MAGMA) [ n le 2 select 2*n-1 else 2*Self(n-2): n in [1..42] ];
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CROSSREFS
| Cf. A000079 (powers of 2), A007283 (3*2^n), A074323, A162255, A048654, A111567, A081179, A164072, A164031.
Sequence in context: A116626 A162255 A074323 * A177828 A090571 A088452
Adjacent sequences: A164070 A164071 A164072 * A164074 A164075 A164076
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KEYWORD
| nonn
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 09 2009
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