A035934 Smallest number that can be made to take n steps to reach 0 under "k -> any product of 2 numbers whose concatenation is k".

0, 1, 11, 26, 39, 77, 117, 139, 429, 529, 777, 1117, 1669, 2238, 2993, 3697, 4779, 5319, 5919, 10998, 11794, 14989, 21179, 26869, 27797, 36177, 38993, 62958, 74297, 85797, 95339, 113319, 125919, 139919, 199683, 201799, 247817, 333329, 360497, 419926

Offset

0,3

Links

Table of n, a(n) for n=0..39.

Example

a(6) = 117 since 117 -> 77 -> 49 -> 36 -> 18 -> 8 -> 0.

Mathematica

tbl=Table[1, {10}]; Do[tbl=Append[tbl, b=IntegerDigits[k]; If[(First[b]==0||Last[b]==0), 1, Max[Part[tbl, Table[FromDigits[Take[b, i]]*FromDigits[Take[b, i-Length[b]]], {i, 1, Length[b]-1}]]]+1]], {k, 11, 170000}]; tbl; m=Max[tbl]; Prepend[Flatten[Table[Position[tbl, i, 1, 1], {i, 1, m}]], 0]

Crossrefs

Cf. A035930-A035935.

Sequence in context: A190684 A354383 A002154 * A035932 A035933 A035935

Adjacent sequences: A035931 A035932 A035933 * A035935 A035936 A035937

Keyword

nonn,base,nice

Author

Erich Friedman

Extensions

More terms from Naohiro Nomoto, Apr 11 2001

More terms from Vit Planocka (planocka(AT)mistral.cz), Feb 01 2003

More terms from Martin Fuller, Jun 02 2006

Status

approved