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 A025728 #12 Jul 06 2025 13:16:11 %S A025728 1,3,7,13,21,31,43,57,73,91,110,131,154,179,206,235,266,299,334,370, %T A025728 408,448,490,534,580,628,678,730,783,838,895,954,1015,1078,1143,1210, %U A025728 1279,1350,1422,1496,1572,1650,1730,1812,1896,1982,2070,2159,2250,2343,2438 %N A025728 Index of 8^n within sequence of numbers of form 3^i*8^j (A025615). %C A025728 Positions of zeros in A025643. - _R. J. Mathar_, Jul 06 2025 %F A025728 A025615(a(n)) = 8^(n-1). - _Bernard Schott_, Dec 27 2021 %Y A025728 Cf. A025615, A025699 (similar for 3^n). %K A025728 nonn %O A025728 1,2 %A A025728 _David W. Wilson_