1,948 years from Adam to Abraham.

http://www.youtube.com/watch?v=WYFs41oLBT4&feature=share

http://www.bible-codes.org/Letters-israel-1948_mirror.htm

And so, like Adam and Noah, Terah also has three children with the promised child not the firstborn. And this pattern continues throughout the bible, for it is not the firstborn that gets the blessing, but it is the promised child, not as of man in the normal way, but by the mercy of God. Not of works lest any man should boast.

http://www.rtmathews.com/?page_id=5