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 A086846 #14 Apr 09 2022 13:22:38 %S A086846 3,10,73,241,2504,10537,124363,573928,7407840,35547994,491316166, %T A086846 2409600865,34896253009,174155363186,2601913448896,13163230391312, %U A086846 201431415980418,1029540512731472 %N A086846 Number of brilliant numbers < 10^n. %o A086846 (PARI) a(n) = my(N=10^n-1, count=0, L=#digits(sqrtint(N))); for(k=1, L-1, count += binomial(primepi(10^k) - primepi(10^(k-1)) + 1, 2)); my(min = 10^(L-1), max = 10^L-1, pi_min = primepi(min), pi_max = primepi(max), j = 0); forprime(p = min, max, if(p*p <= N, count += if(N >= p*max, pi_max, primepi(N\p)) - pi_min - j; j+=1, break)); count; \\ _Daniel Suteu_, Apr 09 2022 %Y A086846 Cf. A078972, A087434, A087435. %K A086846 nonn,more %O A086846 1,1 %A A086846 _Jason Earls_, Aug 09 2003 %E A086846 More terms from _Ray Chandler_, Aug 31 2003 %E A086846 a(11)-a(14) from _Ray Chandler_, Jul 21 2005 %E A086846 a(15)-a(16) from _Donovan Johnson_, May 30 2010 %E A086846 a(17)-a(18) from _Daniel Suteu_, Apr 09 2022