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 A025741 #9 Jul 06 2025 13:44:25 %S A025741 1,4,9,16,25,36,49,64,81,100,121,145,171,199,229,261,295,331,369,409, %T A025741 451,496,543,592,643,696,751,808,867,928,991,1056,1124,1194,1266,1340, %U A025741 1416,1494,1574,1656,1740,1826,1915,2006,2099,2194,2291,2390,2491,2594,2699 %N A025741 Index of 10^n within sequence of numbers of form 3^i*10^j. %C A025741 Positions of zeros in A025644. - _R. J. Mathar_, Jul 06 2025 %H A025741 Charles R Greathouse IV, <a href="/A025741/b025741.txt">Table of n, a(n) for n = 1..10000</a> %o A025741 (PARI) a(n)=my(N=1); n+sum(i=2,n, logint(N*=10,3)); \\ _Charles R Greathouse IV_, Jan 10 2018 %o A025741 (PARI) first(n)=my(s,N=1/10); vector(n,i, s+=logint(N*=10,3)+1) \\ _Charles R Greathouse IV_, Jan 10 2018 %K A025741 nonn,easy %O A025741 1,2 %A A025741 _David W. Wilson_