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 A319809 #13 Oct 26 2018 08:17:00 %S A319809 7794416,7816758,8131871,8132006,8152638,8152650 %N A319809 Numbers k that are equal to 2*k when expressed in base 9 and then interpreted in base 10. %e A319809 8132006 expressed in base 9 is equal to 16264012; 16264012 = 2*8132006. %t A319809 Select[Range[10^6, 10^7], FromDigits@ IntegerDigits[#, 9] == 2 # &] (* _Michael De Vlieger_, Oct 11 2018 *) %o A319809 (PARI) isok(n) = fromdigits(digits(n,9), 10) == 2*n; \\ _Michel Marcus_, Sep 28 2018 %Y A319809 Cf. A139285. %K A319809 nonn,base,fini,full %O A319809 1,1 %A A319809 _Anton Deynega_, Sep 28 2018