`A=1^2+3^2+5^2+...+2021^2`
`=1.1+3.3+5.5+...+2021.2021`
`=1+9+25+...+4084441`
`=10+25+...+4084441`
`=35+...+4084441`
`=4084476`
`B=2^2+4^2+6^2+...+2020^2`
`=2.2+4.4+6.6+...+2020.2020`
`=4+16+36+...+4080400`
`=20+36+...+4080400`
`=56+...+4080400`
`=4080456`