CalcBridgeLenCostFactor
length | 1 | 2 | 3 | 4 | 5 |  6 |  7 |  8 |  9 | 10 | 11 | 12 | 13
sum    | 1 | 2 | 3 | 5 | 7 | 10 | 13 | 16 | 20 | 24 | 28 | 32 | 37
delta  | - | - | 1 | 2 | 2 |  3 |  3 |  3 |  4 |  4 |  4 |  4 |  5