This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A239234 #9 Apr 03 2023 10:36:13 %S A239234 0,2,6,17,36,99,249,651,1774,5018,13587,39170,115968,323061,953827, %T A239234 2870277,8165537,24569821 %N A239234 Number of Proth primes < 10^n. %H A239234 Chris Caldwell, <a href="https://t5k.org/top20/page.php?id=66">The Top 20 Proth Primes</a> %H A239234 Chris Caldwell, The Prime Glossary, <a href="https://t5k.org/glossary/xpage/ProthPrime.html">Proth prime</a> %e A239234 a(2) = 6 since first 6 Proth primes are 3, 5, 13, 17, 41, 97 all < 10^2. %o A239234 (PARI) a(n)=my(c=0); for(m=1, floor(n*log(10)/log(2)), k=1; until(k>2^m, p=k*2^m+1; if(p>10^n, break); if(isprime(p), c++); k=k+2)); c; %Y A239234 Cf. A080076. %K A239234 nonn %O A239234 0,2 %A A239234 _Arkadiusz Wesolowski_, Mar 13 2014