Buck converter inductor calculation doesn't agree with typical application schematic
TI provides the sample design targeting 12V Vin. From the datasheet:



This explains the discrepancy between formulas (that assume 24V Vin) and the value of inductor in the example design. They should however mention this fact in their schematics, which boldly says "4.5V to 24 V", and you can try to advise them to correct the schematics.

However, I think the conversion from 24V to 1.8V is unwise, it will suffer in terms of efficiency.

CORRECTION: It is true that 12V V in doesn't change much the result. However, the whole selection of inductor uses just 30% ripple current at max load, and the datasheet has another note:


  Note:The calculation above shall serve as a general reference. To
  further improve transient response, the output inductance could be
  reduced further. This needs to be considered along with the
  selection of the output capacitor.


So if you (I mean quality of your output capacitor) can afford 75% current swing in the inductor, then all numbers will align.

I would say this: don't confuse yourself with formulas too much, all simplified formulas are derived under many assumptions, which may or may not be exactly true. Always use the manufacturer's reference design as the main guidance. They build it, thoroughly characterized it, and sell it. More, if you want to avoid surprises, follow their recommended (tested!!!) layouts, and get their particular inductor from their BOM - not all inductors are made equal.