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A117713
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a(1)=1, a(2)=3, a(3)=8; for n>=4, a(n) = 10*a(n-3) + 8 (if a(n-3) is odd) or + 9 if a(n-3) is even).
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0
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1, 3, 8, 18, 38, 89, 189, 389, 898, 1898, 3898, 8989, 18989, 38989, 89898, 189898, 389898, 898989, 1898989, 3898989, 8989898, 18989898, 38989898, 89898989, 189898989, 389898989, 898989898, 1898989898, 3898989898, 8989898989, 18989898989, 38989898989, 89898989898
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| From a puzzle (1,3,8,18,?,89,189) given on a civil service test.
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MAPLE
| f:=proc(n) option remember; local t1; if n=1 then RETURN(1); fi; if n=2 then RETURN(3); fi; if n=3 then RETURN(8); fi; t1:=10*f(n-3)+8; if f(n-3) mod 2 = 0 then t1:=t1+1; fi; RETURN(t1); end;
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CROSSREFS
| Sequence in context: A131051 A172265 A117727 * A128552 A011377 A178420
Adjacent sequences: A117710 A117711 A117712 * A117714 A117715 A117716
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KEYWORD
| nonn
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AUTHOR
| Louis Ciotti (lciotti(AT)twcny.rr.com), Apr 13 2006
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EXTENSIONS
| Solution proposed by Mohammed BOUAYOUN (mohammed.bouayoun(AT)yahoo.fr), Apr 14 2006
Another possibility is that 1,3,8,18,?,89,189,... is an erroneous version of A117727. - Hugo van der Sanden (hv(AT)crypt.org), Apr 14 2006
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