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 A025702 #9 Jul 06 2025 13:11:13 %S A025702 1,2,4,7,11,16,22,29,36,44,53,63,74,86,99,112,126,141,157,174,192,211, %T A025702 230,250,271,293,316,340,365,390,416,443,471,500,530,561,593,625,658, %U A025702 692,727,763,800,838,876,915,955,996,1038,1081,1125,1169,1214,1260,1307,1355 %N A025702 Index of 4^n within sequence of numbers of form 4^i*5^j. %C A025702 Positions of zeros in A025650. - _R. J. Mathar_, Jul 06 2025 %H A025702 Charles R Greathouse IV, <a href="/A025702/b025702.txt">Table of n, a(n) for n = 0..10000</a> %o A025702 (PARI) a(n)=my(N=1); n+1+sum(i=1, n, logint(N<<=2, 5)); \\ _Charles R Greathouse IV_, Jan 11 2018 %o A025702 (PARI) first(n)=my(s, N=1/4); vector(n+1, i, s+=logint(N<<=2, 5)+1) \\ _Charles R Greathouse IV_, Jan 11 2018 %Y A025702 Differs from A025717 at a(65). %K A025702 nonn,easy %O A025702 0,2 %A A025702 _David W. Wilson_ %E A025702 Offset corrected by _Charles R Greathouse IV_, Jan 11 2018