HP-80 Unexplained Key Sequence?

[Max Stone]

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

[Massimo Gnerucci]

(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... :)

[Max Stone]

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

Kind regards, MAX

[Martin Paech]

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).

[Martin Paech]

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 sequences…

[bshoring]

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

Bob

[rprosperi]

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?

[HP67]

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

[Thomas Klemm]

(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