A041013 Reverse or double: if reverse of a(n) > a(n), then a(n+1) = a(n) reversed, otherwise a(n+1) = 2*a(n).

1, 2, 4, 8, 16, 61, 122, 221, 442, 884, 1768, 8671, 17342, 24371, 48742, 97484, 194968, 869491, 1738982, 2898371, 5796742, 11593484, 48439511, 96879022, 193758044, 440857391, 881714782, 1763429564, 4659243671, 9318487342, 18636974684, 48647963681

Offset: 0

Author

Dann Toliver

Keywords

• base
• nonn
• nice

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A004086.

Programs

Haskell

a041013 n = a041013_list !! n
a041013_list = 1 : f 1 where
   f x | rev <= x  = (2*x) : f (2*x)
       | otherwise = rev : f rev where rev = a004086 x
-- Reinhard Zumkeller, Aug 08 2011

Mathematica

rd[n_]:=Module[{rev=FromDigits[Reverse[IntegerDigits[n]]]},If[ rev>n, rev, 2n]]; NestList[rd,1,40] (* Harvey P. Dale, Jan 25 2013 *)
NestList[If[IntegerReverse[#]>#,IntegerReverse[#],2#]&,1,40] (* Harvey P. Dale, Aug 23 2023 *)

Extensions

Typo in definition corrected by K. Viswanathan Iyer, Mar 23 2010