[seqfan] Numbers NOT of the form 2^x - y^2

[Alonso Del Arte]

A sequence from Juri-Stepan raises for me a question I find very
interesting: how can you be absolutely sure a number is NOT of the form 2^x
- y^2 ? The answer would also be relevant for the supersequence, A051213.

Since Juri's subsequence consists of the prime numbers of the form, I had
the foggy notion that Legendre's symbol is relevant, but I can't figure out
if I'm on the right track with that.

Al

-- 
Alonso del Arte
Author at SmashWords.com
<https://www.smashwords.com/profile/view/AlonsoDelarte>
Musician at ReverbNation.com <http://www.reverbnation.com/alonsodelarte>