Uban Number

Author

Eric W. Weisstein
November 9, 2003

This notebook downloaded from http://mathworld.wolfram.com/notebooks/IntegerSequences/ObanNumber.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/ObanNumber.html.

©2005 Wolfram Research, Inc. except for portions noted otherwise

Code

UbanNumberQ[n_Integer]:=!StringMatchQ[NumberName[n],"*u*"]

Enumeration

Length[uban=Select[Range[10^4],UbanNumberQ[#]&]]//Timing

Length[uban=Select[Range[10^5],UbanNumberQ[#]&]]//Timing

Length[uban=Select[Range[10^6],UbanNumberQ[#]&]]//Timing

Length[uban=Select[Join[Range[99],
Sequence@@Table[Range[n 10^6,n 10^6+99],{n,9}]
],UbanNumberQ[#]&]]//Timing

UbanNumberQ/@And@@uban

fourless=Take[Select[Range[800],!MemberQ[IntegerDigits[#],4]&],500];

Take[Complement[fourless,uban],20]

Take[Complement[uban,fourless],20]

uban

Binary

<<Utilities`Plot`

Show[PixelPerfect[BasePlot[Take[uban,255]],BlockSize->2]]

Show[PixelPerfect[BasePlot[Take[uban,{256,256+2 255}]],BlockSize->1]]