802.11n router supporting 802.11n as WAN connection?

I have an existing 802.11n WLAN router with an Ethernet connection as its upstream WAN connection (router A). I would like to get another 802.11n WLAN router (router B) and have it use router A as its upstream WAN connection. Router B needs to connect to router A via 802.11n with WPA2 security.

Is this possible? Any WLAN routers support this notion of connecting to anothe WLAN router as its upstream WAN connection?

Thanks.