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Cool, I hadn't run into it before so thanks for introducing me! I was going to include the digits for comparison, but yes, on second thought 6002 digits is pro
by jdewerd 2y ago
Cool, I hadn't run into it before so thanks for introducing me!
I was going to include the digits for comparison, but yes, on second thought 6002 digits is probably too much for polite inclusion in a HN post.
- shric 2y agoYeah, although that's better than 19937 ones in a row.
- quuxplusone 2y agohttps://oeis.org/A004023 https://oeis.org/A004023 "Indices of prime repunits: numbers k such that 11...111 (with k 1's) = (10^k - 1)/9 is prime." OEIS says "19937 ones in a row" isn't prime, but "1031 ones in a row" is. And "8177207 ones in a row" is at least a probable prime. (Which you can maybe remember as a seven-digit phone number, or as either BITTZOT or LOZLLIB depending on how you prefer to hold your calculator. But those mnemonics are wasted if (10^{81777207}-1)/9 turns out to be merely pseudoprime.)