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A117600
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Padovan numbers for which the multiplicative digital root is also a Padovan number.
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1
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0, 1, 2, 3, 4, 5, 7, 9, 12, 21, 37, 65, 114, 151, 200, 265, 351, 465, 1081, 1897, 2513, 3329, 4410, 5842, 10252, 13581, 17991, 31572, 41824, 55405, 73396, 128801, 170625, 226030, 299426, 396655, 525456, 696081, 1221537, 2143648, 2839729, 3761840, 4983377
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OFFSET
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1,3
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LINKS
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MAPLE
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Padovan := proc(n) option remember: if(n=0)then return 1:elif(n<=2)then return 0:fi: return procname(n-3) + procname(n-2): end: MultDig := proc(n) return mul(d, d=convert(n, base, 10)): end: MultRoot := proc(n) local m: m:=n: while(length(m)>1)do m:=MultDig(m): od: return m: end: A117600ind := proc(n) option remember: local k: if(n=1)then return 4:fi: for k from procname(n-1)+1 do if(not Padovan(k)=Padovan(procname(n-1)) and MultRoot(Padovan(k)) in {0, 1, 2, 3, 4, 5, 7, 9})then return k: fi: od: end: seq(Padovan(A117600ind(n)), n=1..60); # Nathaniel Johnston, May 05 2011
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CROSSREFS
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KEYWORD
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nonn,easy,base
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AUTHOR
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Luc Stevens (lms022(AT)yahoo.com), Apr 05 2006
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EXTENSIONS
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STATUS
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approved
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