A097156 Least number that requires exactly n iterations of f(x) = reverse(x) - maxdigit(x) to reach zero.

1, 11, 16, 12, 15, 25, 36, 106, 104, 108, 197, 1009, 1022, 1052, 1091, 1073, 1801, 10004, 10005, 10051, 10062, 10071, 10083, 10081, 10092, 14991, 19982, 19991, 100092, 100192, 100282, 100191, 107991, 101973, 289101, 1000094, 1000084

Offset

1,2

Links

Table of n, a(n) for n=1..37.

Example

a(5)=15 because 15 -> 46 -> 58 -> 77 -> 70 -> 0 takes five steps to reach zero.

Mathematica

g[n_] := Block[{id = IntegerDigits[n]}, ie = FromDigits[ Reverse[id]] - Union[id][[ -1]]; If[ie == 89, 0, ie]]; h[n_] := Length[NestWhileList[g, n, UnsameQ, All]] - 2; Do[ a = h[n]; If[a < 51 && t[[a]] == 0, t[[a]] = n], {n, 10^6}] (* Robert G. Wilson v, Aug 13 2004 *)

Crossrefs

Cf. A097153, A097154, A097155, A097157, A097158.

Sequence in context: A147339 A147377 A147333 * A138791 A132990 A074197

Adjacent sequences: A097153 A097154 A097155 * A097157 A097158 A097159

Keyword

base,nonn

Author

Jason Earls, Aug 01 2004

Extensions

More terms from Robert G. Wilson v, Aug 13 2004

Status

approved