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 A025709 #14 Jul 06 2025 12:38:06 %S A025709 1,2,4,7,11,15,20,26,33,40,48,57,67,78,89,101,114,128,142,157,173,190, %T A025709 208,226,245,265,286,307,329,352,376,400,425,451,478,506,534,563,593, %U A025709 624,655,687,720,754,789,824,860,897,935,973,1012,1052,1093,1135,1177,1220 %N A025709 Index of 5^n within sequence of numbers of form 5^i*8^j. %C A025709 Positions of zeros in A025673. - _R. J. Mathar_, Jul 06 2025 %o A025709 (PARI) a(n)=my(N=1); n+1+sum(i=1, n, logint(N*=5, 8)); \\ _Charles R Greathouse IV_, Jan 16 2018 %o A025709 (PARI) first(n)=my(s, N=1/5); vector(n+1, i, s+=logint(N*=5, 8)+1) \\ _Charles R Greathouse IV_, Jan 16 2018 %Y A025709 Cf. A025623. Differs from A025703 at a(84). %K A025709 nonn %O A025709 1,2 %A A025709 _David W. Wilson_