It sounds like you have stumbled upon something specific regarding the (which is commonly abbreviated as ESXi 6.0 U1 or sometimes referenced as build 3029758, where the number 41 might relate to a specific build iteration or download identifier in a repository).
Get-FileHash -Algorithm MD5 .\esx-4.1.0-260247.iso esx 41 iso verified
The command will output a string of 32 alphanumeric characters. VMware ESXi 6
Modern hardware often lacks drivers in the standard 4.1 ISO. You may need to inject Community VIBs or drivers for SATA controllers and NICs. Manual Method: esx 41 iso verified