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 A373448 #15 Jun 16 2024 16:46:19 %S A373448 0,27,2313,249903,24183069,2258634081,249410097687,24350854001805, %T A373448 2229543293296319,248640535848971067,24502928886295666773, %U A373448 2255382216082613264687,247524358984342778844555,24637651997205933916917957,2280497169597819727642768343,246037303364254649637740936547 %N A373448 10^n-th binary palindrome. %C A373448 a(n) = A006995(10^n). %H A373448 Chai Wah Wu, <a href="/A373448/b373448.txt">Table of n, a(n) for n = 0..500</a> %o A373448 (Python) %o A373448 def A373448(n): %o A373448 if n == 0: return 0 %o A373448 k = 10**n %o A373448 a = 1<<(l:=k.bit_length()-2) %o A373448 m = a|(k&a-1) %o A373448 return (m<<l+1)+int(bin(m)[:1:-1]or'0',2) if a&k else (m<<l)+int(bin(m)[-2:1:-1]or'0',2) %o A373448 (PARI) a(n) = A006995(10^n); \\ using A006995 PARI program; _Michel Marcus_, Jun 16 2024 %Y A373448 Cf. A002113, A006995, A083816, A099280. %K A373448 nonn,base %O A373448 0,2 %A A373448 _Chai Wah Wu_, Jun 14 2024