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Search: id:A119563
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| A119563 |
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Define F(n) = 2^(2^n)+1 = n-th Fermat number, M(n) = 2^n-1 = the n-th Mersenne number. Then a(n) = F(n)+M(n)-1 = 2^(2^n) + 2^n - 1. |
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3
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| 2, 5, 19, 263, 65551, 4294967327, 18446744073709551679, 340282366920938463463374607431768211583, 115792089237316195423570985008687907853269984665640564039457584007913129640191
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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The first 5 entries are primes. Are there infinitely many primes in this sequence?
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FORMULA
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a(n) = A119561(n)-2=A000215(n)+A000225(n)-1. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 22 2007
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EXAMPLE
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F(2) = 2^(2^2)+1 = 17, M(2) = 2^2-1 = 3, F(2)+ M(2) - 1 = 19
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PROGRAM
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(PARI) fm3(n) = for(x=0, n, y=2^(2^x)+2^x-1; print1(y", "))
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CROSSREFS
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Sequence in context: A080280 A055813 A119550 this_sequence A059079 A136900 A136898
Adjacent sequences: A119560 A119561 A119562 this_sequence A119564 A119565 A119566
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KEYWORD
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nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), May 31 2006
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EXTENSIONS
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Edited by njas, Jun 03 2006
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