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 A059707 If all digits have the same parity, stop; otherwise write down the number formed by the even digits and the number formed by the odd digits and multiply them; repeat. 4
 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 11, 2, 13, 4, 15, 6, 17, 8, 19, 20, 2, 22, 6, 24, 0, 26, 4, 28, 8, 0, 31, 6, 33, 2, 35, 8, 37, 24, 39, 40, 4, 42, 2, 44, 20, 46, 28, 48, 8, 0, 51, 0, 53, 20, 55, 0, 57, 40, 59, 60, 6, 62, 8, 64, 0, 66, 42, 68, 20, 0, 71, 4, 73, 28, 75, 42 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(A059708(n)) = A059708(n). - Reinhard Zumkeller, Jun 15 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..10000 EXAMPLE 89 -> 8*9 = 72 -> 7*2 = 14 -> 1*4 = 4, stop, so a(89) = 4. 33278 -> 28*337 = 9436 -> 46*93 = 4278 -> 42*78 -> 2996 -> 26*99 = 2574 -> 24*57 = 1368 -> 68*13 = 884, stop, so a(33278) = 884. MATHEMATICA f[n_] := (id = IntegerDigits[n]; oddDigits = Select[id, OddQ]; evenDigits = Select[id, EvenQ]; Which[oddDigits == {}, FromDigits[evenDigits], evenDigits == {}, FromDigits[oddDigits], True, FromDigits[evenDigits] * FromDigits[oddDigits]]); a[n_] := FixedPoint[f, n]; Table[a[n], {n, 0, 76}] (* Jean-François Alcover, May 16 2013 *) sp[n_]:=Module[{idn=IntegerDigits[n], e, o}, e=Select[idn, EvenQ]; o= Select[ idn, OddQ]; If[Min[Length[o], Length[e]]>0, FromDigits[o] FromDigits[e], n]]; Table[FixedPoint[sp, i], {i, 0, 80}] (* Harvey P. Dale, Jun 05 2014 *) PROG (Haskell) import Data.List (unfoldr) a059707 n = if u == n || v == n then n else a059707 (u * v) where    (u, v) = foldl (\(x, y) d -> if odd d then (10*x+d, y) else (x, 10*y+d))         (0, 0) \$ reverse \$ unfoldr         (\z -> if z == 0 then Nothing else Just \$ swap \$ divMod z 10) n -- Reinhard Zumkeller, Jun 15 2012 CROSSREFS Cf. A059708, A059717. Sequence in context: A195833 A257294 A139281 * A256754 A265525 A056967 Adjacent sequences:  A059704 A059705 A059706 * A059708 A059709 A059710 KEYWORD nonn,base,easy,nice,look AUTHOR N. J. A. Sloane, Feb 07 2001 EXTENSIONS a(50) corrected by Reinhard Zumkeller, Jun 15 2012 STATUS approved

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Last modified September 18 20:22 EDT 2019. Contains 327181 sequences. (Running on oeis4.)