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 A255971 #18 Jul 19 2025 10:12:36
%S A255971 0,1,1,1,11,168,2356,28321,326831,3678318,39570252,418509525
%N A255971 Number of terms in A255967 less than 10^n.
%o A255971 (PARI) isA255967(m) = if(!(m % 2), 0, my(pow = 2); while(pow < m && !isprime(m - pow) && !isprime(m + pow), pow *= 2); pow > m);
%o A255971 list(len) = {my(pow = 10, c = 0); print1(0, ", "); for(k = 1, 10^len, if(isA255967(k), c++); if(k == pow-1, print1(c, ", "); pow *= 10));} \\ _Amiram Eldar_, Jul 19 2025
%Y A255971 Cf. A254248, A255816, A255967, A256164, A256238.
%K A255971 nonn,more
%O A255971 0,5
%A A255971 _Arkadiusz Wesolowski_, Mar 12 2015
%E A255971 a(9)-a(11) from _Amiram Eldar_, Jul 19 2025