Why is the data format for block height in coinbase scriptSigs inconsistent for heights 1-16?
The actual encodings of the numbers 1-16 are 0x51, 0x52, etc. This is because the numbers 1-16 are special in Bitcoin script and have their own explicit opcodes. OP_1 is 0x51, OP_2 is 0x52, etc. The correct way to write numbers with their own opcodes is to use those opcodes instead of using a pushdata opcode followed by the number.