A tricky batch of four number sequences

Question

What are the next few numbers in each of these integer sequences? Each of them has a clear and justifiable solution.

1, 2, 3, 5, 8, 9, 12, 20, 21, 22, ??, ??, ...
50, 49, 48, 46, 45, 44, 43, 38, ..., 25, 24, 23, ??, ??, ...
11, 12, 20, 30, 80, 90, 10000, ????
... 4, 5, 6, 8, 10, 40, 46, 60, 61, ??, ??, ...

leoll2 · Accepted Answer

Partial answer

1)

Ordinal numbers that aren't made juxtaposing the cardinal and "-th" suffix.
Credit of this answer to Xyuzhg

3)

Numbers that when written have exactly 6 letters. 10000=myriad.

4)

Nonnegative integers that when written out in full in English have no repeated letter.

Ben Frankel · Answer

1) All numbers when written out (googol would be ten duotrigintillion) end in one of these letters: denortxy (sorted alphabetically). Take only the even spots of "denortxy" to get "eoty", and now all numbers ending in a letter from "eoty" are in our list.

Answered by Ben Frankel on October 7, 2020

Xyuzhg · Answer

Sequence 1:

Reason:

Alex Rohr · Answer

Sequence 2:

my closest guess anyways

Developer · Answer

The second sequence is:

And the pattern is

Kristian Forde · Answer

A tricky batch of four number sequences

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