We’ve updated our Terms of Service. A new AI Addendum clarifies how Stack Overflow utilizes AI interactions.

Return to Revisions

Jelly, (削除) 13 10 (削除ここまで) 9 bytes

-3 bytes porting Dominic van Essen's implementation of my approach.
-1 byte thanks to Unrelated String (golfing the ¬ out by using a divisibility check.)

b3ḢḂȧ)3ḍS

Try it online! Or see the test-suite.

How?

b3ḢḂȧ)3ḍS - Link: non-negative integer, N
 ) - for each {I in [1..N] ([] if N==0)}:
b3 - convert {I} to base three
 Ḣ - head of {that}
 Ḃ - {that} mod two
 ȧ - {that} logical AND {N}
 3ḍ - three divides {that}? (vectorises)
 S - sum

---

Alternative 9

^{Also seems to be a little more efficient, I'm not sure why.}

Try it online!

bḢ’+ọðƇ3L - Link: non-negative integer, N
 Ƈ - keep those i of [1..N] for which:
 ð 3 - f(i, 3):
b - convert {i} to base {3}
 Ḣ - head of {that} -> first trit (2 or 1)
 ’ - decrement {that} -> L (1 or 0)
 ọ - {i} order {3} (repeated divisibility count)
 + - {L} add {that}
 L - length