1099-R final figures on 1040

I entered my wife's 1099-R amount of 400,723.16, a rollover amount from her 401k to a traditional IRA. On my final filing form Turbo Tax entered these numbers: line 4c  443,333.

Line 4b  26,466.

Line 4d  42,570.

In between lines b and d is the word 'rollover.' I can't figure out where these numbers came from; there is no explanation on the worksheets. Can you help explain?