As character names:
U+BFFFF <not a character> character ()
As raw characters:
As a string of HTML entities:

Decoder output:
Byte number 1 is decimal 242, hex 0xF2, octal \362, binary 11110010 This is the first byte of a 4 byte sequence. Byte number 2 is decimal 191, hex 0xBF, octal \277, binary 10111111 This is continuation byte 1, expecting 2 more. Byte number 3 is decimal 191, hex 0xBF, octal \277, binary 10111111 This is continuation byte 2, expecting 1 more. Byte number 4 is decimal 191, hex 0xBF, octal \277, binary 10111111 This is continuation byte 3, expecting 0 more. U+BFFFF <not a character>