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Search: id:A085613
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| A085613 |
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a(n) = 2^(n-1) + (2 + (-1)^n)^((n-2)/2). |
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+0
1
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| 2, 3, 5, 11, 17, 41, 65, 155, 257, 593, 1025, 2291, 4097, 8921, 16385, 34955, 65537, 137633, 262145, 543971, 1048577, 2156201, 4194305, 8565755, 16777217, 34085873, 67108865, 135812051, 268435457, 541653881, 1073741825
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OFFSET
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1,1
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COMMENT
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Extends Euler's 6-term sequence.
In Euler's 6-term sequence we have noticed that e(1) = 2 = 2^0 + 1; e(2) = 3 = 2^1 + 3^0; e(3) = 5 = 2^2 + 1; e(4) = 11 = 2^3 + 3^1; e(5) = 17 = 2^4 + 1; e(6) = 41 = 2^5 + 3^2, which of course immediately leads to our formula above. Note: For m>0, we take m^(1/2) to be the unique positive square root of m.
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EXAMPLE
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a(2^n + 1), n=0,1,2,... are the Fermat numbers.
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CROSSREFS
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Cf. A082605.
Sequence in context: A014210 A014556 A062737 this_sequence A082605 A007755 A060611
Adjacent sequences: A085610 A085611 A085612 this_sequence A085614 A085615 A085616
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KEYWORD
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nonn
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AUTHOR
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Ben de la Rosa & Johan Meyer (MeyerJH.sci(AT)mail.uovs.ac.za), Jul 09 2003
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EXTENSIONS
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More terms from Neven Juric, Apr 10 2008
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