http://lenschulwitz.com/base58
I tested these Bitcoin-addresses 35-byte length:
Mo111111111111111111111111111111111 (Base58)
0BB52C7E52DC7D16D2A362767FE633FE3751B8D2E73C00000000 (hex)
Mozzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz (Base58)
0BB7A8B59E7FB242C83304156096CABFCE80B3AB9875FFFFFFFF (hex)
Ro111111111111111111111111111111111 (Base58)
0DF5BE9ADEC4ACED5CCDDA721FEED36F39E50D3383CC00000000 (hex)
Rozzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz (Base58)
0DF83AD22A67E219525D7C11009F6A30D114080C3505FFFFFFFF (hex)
As you can see, the first tree octets (1.5 bytes) are always identical in each hex addresses.
base58Prefixes[PUBKEY_ADDRESS] = std::vector
?
0B (hex) = 11 (dec)
B6 (hex) = 182 (dec)
base58Prefixes[PUBKEY_ADDRESS] = std::vector(11,182);
If you want "Ro":
0D (hex) = 13 (dec)
F6 (hex) = 246 (dec)
base58Prefixes[PUBKEY_ADDRESS] = std::vector(13,246);