A051811 Numbers with nonzero multiplicative digital root 9.

9, 19, 33, 90, 91, 109, 119, 133, 190, 191, 259, 295, 303, 313, 330, 331, 356, 365, 529, 536, 563, 592, 635, 653, 900, 901, 910, 911, 925, 952, 1009, 1019, 1033, 1090, 1091, 1109, 1119, 1133, 1190, 1191, 1259, 1295, 1303

Offset: 1

Author

Dan Hoey, Dec 09 1999

Keywords

• nonn
• easy
• base

Links

• Index entries for 10-automatic sequences.

Crossrefs

Part of histogram of A051802.

Programs

Mathematica

nzdr9[n_]:=Module[{idn=Select[IntegerDigits[n],#!=0&]},Times@@idn]; nzdrQ[ n_]:= NestWhile[nzdr9[#]&,n,#>9&]==9; Select[Range[2000],nzdrQ] (* Harvey P. Dale, Sep 09 2014 *)

Formula

A051802^-1(9)