Sunday, October 29, 2023

Bucket list #2

My original five-piece bucket list is here with #3 here.

2. China Town (Their online ordering system stopped working a few years ago.)

1790 Jane Street @ John Street

The picture is Google street view (July 2023). I did eventually find another website ordering system for them but I was reluctant to use it in case it was a scam. Researching the website provider (MealKeyway), I decided finally that it was ok.

3 large Beef Fried Rice (no onion) $22.47; Sweet & Sour Chicken Balls $11.99; Fried Mixed Vegetables (no onion) $9.99; there's a $40 minimum food-only order; tax $5.78; delivery $4.99; tip $3.00; rounding -$0.02: total $58.20

Pretty much the way I remembered it, although I used to get BBQ chicken wings as well. I hadn't before used a no-onion option on the mixed vegetables. They replaced it with more broccoli which (unfortunately) was excessively salty. I guess the florets/buds retain a lot of the briny broth. I can run them under the faucet in the leftover reheats.

Saturday, October 28, 2023

Tuesday, October 24, 2023

AD one billion

√Čric Angelini's latest offering is based on the absolute differences (AD, be they odd or even) of an integer sequence's adjacent digits determining the sequence's new numbers. After Giorgos Kalogeropoulos posted one million terms, I struggled to better his (apparently Mathematica) result to five million terms before realizing that my one-at-a-time AppendTo approach was not the best tool for this game.

Starting with 315 terms of the sequence (s) we generate — in twelve steps — over one billion terms by repetitively determining the adjacent-digits sequence, creating therefrom an absolute differences sequence, and applying a sign change to those differences that are even. Prepend zero, Accumulate, add 10.

Table[d=Flatten[IntegerDigits[s]]; c=Abs[Most[d]-Rest[d]]; f=Prepend[Table[If[OddQ[c[[i]]],c[[i]],-c[[i]]], {i,Length[c]}], 0]; s=Accumulate[f]+10; Length[s], {12}]

{577, 1181, 2719, 6976, 19556, 57525, 203635, 791890, 3733165, 21270116, 140287834, 1002951921}

That's it! Truncate the final 1002951921 terms to 10^9 terms, take every tenth integer (Mathematica has trouble enough plotting 100 million points), and graph:

click to enlarge