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Search: id:A131570
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| A131570 |
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a(1) = 1; for n >= 1, if a(n) is odd then a(n+1) = a(n) followed by a(n)+1, but if a(n) is even then a(n+1) = a(n)/2. |
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1
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| 1, 12, 6, 3, 34, 17, 1718, 859, 859860, 429930, 214965, 214965214966, 107482607483, 107482607483107482607484, 53741303741553741303742, 26870651870776870651871, 2687065187077687065187126870651870776870651872
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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17 is odd so the next term is 1718; 1718 is even so the next term is 1718/2 = 859.
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MAPLE
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catL := proc(a, b) a*10^( max(ilog10(b)+1, 1)) +b ; end: A131570 := proc(n) option remember ; local prev; if n = 1 then 1 ; else prev := A131570(n-1) ; if prev mod 2 = 1 then catL(prev, prev+1) ; else prev/2 ; fi ; fi ; end: seq(A131570(n), n=1..20) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 26 2007
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MATHEMATICA
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a = {1}; Do[If[OddQ[a[[ -1]]], AppendTo[a, FromDigits[Join[IntegerDigits[a[[ -1]]], IntegerDigits[a[[ -1]] + 1]]]], AppendTo[a, a[[ -1]]/2]], {25}]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Oct 26 2007
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CROSSREFS
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Sequence in context: A028578 A013680 A033963 this_sequence A033332 A051725 A070292
Adjacent sequences: A131567 A131568 A131569 this_sequence A131571 A131572 A131573
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KEYWORD
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nonn,base
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AUTHOR
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Rodolfo Kurchan (rodolfokurchan(AT)yahoo.com.ar), Aug 27 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Oct 26 2007
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