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 A256164 #17 Jul 19 2025 10:12:56
%S A256164 0,1,1,1,3,10,161,2342,27216,317155,3505277,38127106
%N A256164 Number of terms in A256163 less than 10^n.
%o A256164 (PARI) isA256163(m) = if(!(m % 2), 0, my(pow = 2); while(pow < m && !isprime(m - pow) && !isprime(m + pow) && !isprime(m*pow - 1) && !isprime(m*pow + 1), pow *= 2); pow > m);
%o A256164 list(len) = {my(pow = 10, c = 0); print1(0, ", "); for(k = 1, 10^len, if(isA256163(k), c++); if(k == pow-1, print1(c, ", "); pow *= 10));} \\ _Amiram Eldar_, Jul 19 2025
%Y A256164 Cf. A254248, A255816, A255971, A256163, A256238.
%K A256164 nonn,more
%O A256164 0,5
%A A256164 _Arkadiusz Wesolowski_, Mar 17 2015
%E A256164 a(9)-a(11) from _Amiram Eldar_, Jul 19 2025