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Search: id:A001685
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| A001685 |
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a(0) = 1, a(1) = 2, a(2) = 3; for n >= 3, a(n) = a(n-2) + a(n-1)*prod_{i=1..n-3} a(i).
(Formerly M0740 N0278)
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+0
8
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| 1, 2, 3, 5, 13, 83, 2503, 976253, 31601312113, 2560404986164794683, 202523113189037952478722304798003, 506227391211661106785411233681995783881012463859772443053
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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From a continued fraction.
Every term is relatively prime to all others. - Michael Somos Feb 01 2004
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REFERENCES
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V. C. Harris, Another proof of the infinitude of primes, Amer. Math. Monthly, 63 (1956), 711.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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PROGRAM
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(PARI) a(n)=if(n<3, max(0, n+1), a(n-2)+a(n-1)*prod(i=1, n-3, a(i))) - Michael Somos Feb 01 2004
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CROSSREFS
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Cf. A003686, A064526.
Sequence in context: A042695 A074394 A056162 this_sequence A074691 A139589 A152114
Adjacent sequences: A001682 A001683 A001684 this_sequence A001686 A001687 A001688
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Jun 12 2006
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