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A133400
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a(0)=a(1)=a(2) = 1, thereafter a(n) = a(n-1)*a(n-2)*a(n-3) + 1.
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1
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1, 1, 1, 2, 3, 7, 43, 904, 272105, 10577265561, 2601826668310218121, 7488387181338771882437732599874506, 206081999881071045385328009597554265108557649484947339933019787
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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COMMENTS
| A tribonacci analogue of A001056.
a(13) has 115 digits. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 10 2007
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EXAMPLE
| a(8) = a(7)*a(6)*a(5) + 1 = 904 * 43 * 7 + 1 = 272105.
a(9) ~ 2.60182667 * 10^18.
a(10) ~ 7.48838719 * 10^33.
a(11) ~ 2.06082 * 10^62.
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MAPLE
| A133400 := proc(n) local i ; if n <= 2 then 1; else 1+mul( A133400(i), i=n-3..n-1) ; fi ; end: seq(A133400(n), n=0..15) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 10 2007
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CROSSREFS
| Cf. A001056.
Sequence in context: A091771 A072714 A051786 * A113845 A072713 A129871
Adjacent sequences: A133397 A133398 A133399 * A133401 A133402 A133403
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 24 2007, Nov 26 2007
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 10 2007
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