OFFSET
0,3
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
KEYWORD
nonn,base,nice
AUTHOR
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