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 A117713 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). 0
 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; text; internal format)
 OFFSET 1,2 COMMENTS From a puzzle (1,3,8,18,?,89,189) given on a civil service test. LINKS 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; CROSSREFS Sequence in context: A172265 A258272 A117727 * A128552 A238361 A011377 Adjacent sequences: A117710 A117711 A117712 * A117714 A117715 A117716 KEYWORD nonn AUTHOR Louis Ciotti (lciotti(AT)twcny.rr.com), Apr 13 2006 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, Apr 14 2006 STATUS approved

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Last modified December 1 05:02 EST 2022. Contains 358454 sequences. (Running on oeis4.)