[seqfan] Two "dumb" sequences and a question
Ali Sada
pemd70 at yahoo.com
Wed Nov 30 12:58:06 CET 2022
Hi everyone,
Please consider the two sequences below:
1) Sequence AX contains all OEIS sequences where the A number is a term in the sequence itself. For example, A000027 since 27 is a positive integer.
2) Sequence AY contains all OEIS sequences where either:
a) the A number is not a term in the sequence (e.g., A000040, since 40 is not a prime number),
or
b) we don’t know if the A number is a term in the sequence or not (e.g., A329697).
The question here is: Where should the number Y go? If we put it in sequence AY, then we know where it belongs and that contradicts the definition of AY.
Also, it couldn’t be part of AX because Y is not a term of AY.
I’m trying to have some basic understanding of set theory and I would really appreciate your feedback.
Best,
Ali
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