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A072560
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Denominators of w(n) where w(1)=w(2)=w(3)=1, w(n)=(w(n-1)*w(n-2)+(w(n-1)+w(n-2))/3) / w(n-3).
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3
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3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Sequence contains 1,3 or 9 only and is periodic with period (3,9,3,3,1,3,3,9,3,3,1,3,3,9,3,1,1,1) of length 18.
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FORMULA
| a(n)=1/1377*{-122*(n mod 18)+31*[(n+1) mod 18]+31*[(n+2) mod 18]+184*[(n+3) mod 18]+490*[(n+4) mod 18]-428*[(n+5) mod 18]+31*[(n+6) mod 18]-122*[(n+7) mod 18]+184*[(n+8) mod 18]+31*[(n+9) mod 18]+490*[(n+10) mod 18]-428*[(n+11) mod 18]+31*[(n+12) mod 18]-122*[(n+13) mod 18]+184*[(n+14) mod 18]+31*[(n+15) mod 18]+490*[(n+16) mod 18]-428*[(n+17) mod 18]} with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Nov 29 2006
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CROSSREFS
| Cf. A072561, A072557.
Sequence in context: A016674 A091670 A201416 * A074959 A010632 A195292
Adjacent sequences: A072557 A072558 A072559 * A072561 A072562 A072563
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 06 2002
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