Achyut Posted May 13, 2020 Share Posted May 13, 2020 Do it if you like !!! 👍All the best👍 Link to comment Share on other sites More sharing options...
Strange Posted May 13, 2020 Share Posted May 13, 2020 ! Moderator Note Moved to Puzzles section Spoilers: https://oeis.org/A000043 https://www.wolframalpha.com/input/?i=factorise+(2^92+-+1) Link to comment Share on other sites More sharing options...
Sensei Posted May 13, 2020 Share Posted May 13, 2020 50 minutes ago, Strange said: r https://www.wolframalpha.com/input/?i=factorise+(2^92+-+1) ..but OP nowhere said it is sequence of binary ones.. 2 Link to comment Share on other sites More sharing options...
Strange Posted May 13, 2020 Share Posted May 13, 2020 51 minutes ago, Sensei said: ..but OP nowhere said it is sequence of binary ones.. Very good point! Link to comment Share on other sites More sharing options...
joigus Posted May 13, 2020 Share Posted May 13, 2020 4 hours ago, Sensei said: ..but OP nowhere said it is sequence of binary ones.. Right you are. My doctor told me to stay away from factorizing numbers that are too high. Link to comment Share on other sites More sharing options...
Sensei Posted May 13, 2020 Share Posted May 13, 2020 4 hours ago, joigus said: My doctor told me to stay away from factorizing numbers that are too high. Why? Change doctor It is easy.. If you have decimal e.g. 1111 factors will be 101 and 11. If it is e.g. 111111 factors will be 1001 and 111. And so on. You just have to answer question if number of decimal ones is dividable and has factors by itself. 91 is not prime. It is dividable by 7 and 13. 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 is dividable by 1111111. 2 Link to comment Share on other sites More sharing options...
Strange Posted May 13, 2020 Share Posted May 13, 2020 So, as expected, the answer is the same whether we assume it is binary or decimal. Link to comment Share on other sites More sharing options...
joigus Posted May 13, 2020 Share Posted May 13, 2020 40 minutes ago, Sensei said: Why? Change doctor It is easy.. If you have decimal e.g. 1111 factors will be 101 and 11. If it is e.g. 111111 factors will be 1001 and 111. And so on. You just have to answer question if number of decimal ones is dividable and has factors by itself. 91 is not prime. It is dividable by 7 and 13. 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 1111111 is dividable by 1111111. Oh, yeah, divisibility by 11 criteria give you that, right? I'd forgotten about that. Must go over that again. But don't get me into other numbers. Link to comment Share on other sites More sharing options...
John Cuthber Posted May 14, 2020 Share Posted May 14, 2020 https://en.wikipedia.org/wiki/Repunit 1 Link to comment Share on other sites More sharing options...
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