Is it necessary in the 15 nH inductor in the DC-DC converter?

[Mikhail]

In this scheme we use 2 inductor in a serial connection. 15 nH + 10 uH. Total inductor = 10.015 uH. ??? Is really need to add this 15 nH inductor? For why? If we just short circut this 15 nH? We will have total inductor is 10 uH. I think, this is enought for DC-DC converter. Isn't it?

Can I don't use this 15 nH and solder only 10 uH? 

[Denis Rustak]

It's pretty much required, unless you have incredible components; see here https://devzone.nordicsemi.com/f/nordic-q-a/10104/inductor-considerations-for-nrf-52832-dc-dc-converter

It's the same general idea as capacitors in parallel were each one presents a low impedance over a certain frequency range as others fall into self-resonance.

Here the inductors are in series and the 10uH one will start to look like a low impedance at higher frequencies.  The 15nH one comes into play at that point, ensuring the whole thing doesn't look like a dead-short at the high end.