HP ported their calculators to iPhone and Android apps. Most people who want an HP calc probably just use those now instead, except for the few who want the tactile feel of calculator buttons.
HP didn't even extend a courtesy reach-around for our CS/CpE brethren with 16c integration despite their $16.99! Even if you were in the market circa 2011 to pre-order one (or a few) 15c LE--which came with a copy of the desktop app--you'd still have to pony up even more for the mobile app!
On Android, I'd highly recommend skipping the "official" HP garbage and supporting CalcTastic Plus[1] for a mere $0.99. Even the free version makes the HP emulator look like a complete joke. I've been rolling with a 35s as workhorse since undergrad days, but couldn't care less if today's zombie HP literally disappeared from the market tomorrow.
[1] https://play.google.com/store/apps/details?id=com.shaytastic...