Can anyone tell me why the HP-80 gives this unusual, unexplained sequence when you keep pressing Shift then the Decimal Point, giving you the following sequence (from an empty stack):

0.

1.

2.

3.

5.

11.

26.

66.

227.

1064.

6257.

62979.

1251797.

41590664.

4048283972.

Kind regards, MAX

(06-21-2014 07:37 PM)Max Stone Wrote: [ -> ]Can anyone tell me why the HP-80 gives this unusual, unexplained sequence when you keep pressing Shift then the Decimal Point, giving you the following sequence (from an empty stack):

0.

1.

2.

3.

5.

11.

26.

66.

227.

1064.

6257.

62979.

1251797.

41590664.

4048283972.

Kind regards, MAX

We've already been

here... :)

Thanks, interesting...one of those unexplained features of these early HP calculators.

Kind regards, MAX

Unfortunately, with respect to the HP-80 I can't help, but this sequence (apparently) of integers might be of general interest (it's not in the

OEIS).

Thank you for the link, Massimo! Gerson W. Barbosa has also checked the OEIS in 2012: How about to publish this curious sequence?

Martin

Edit: Till now HP is only mentioned in

two sequencesâ€¦

Max, does this also change the display on yours to zero places? On my HP-80 iOS emulator it does.

Bob

By coincidence, I just got a beautiful HP-80 from TAS 2 days ago, and while playing with it, I entered repeated 8's to verify the LED segments, and discovered it does a similar (by that I mean unexpected) thing.

Initially of course, it fills the display left to right, but once filled, the exponent field grows by 1 for each addional press of 8, or indeed any numeric entry key.

As noted above, just another unexpected result (as opposed to bug I suppose) which was 'corrected' in later models.

Of interest, the s/n begins 1247... meaning one of the earlier units produced, since Introduction was 1973. The HP-35 2.02 bug is well known, but are there analogous HP-80 bugs in history books?

Wow, what a beautiful calculator. I had to look that one up. I had not heard about it.

(06-22-2014 05:36 PM)rprosperi Wrote: [ -> ]The HP-35 2.02 bug is well known, but are there analogous HP-80 bugs in history books?

There's a

display bug (search for the title: "End Note - Bugs?") and another one concerning \(\Sigma\)+ described in my

Message #10 posted on 13 Feb 2012.

Cheers

Thomas