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 A200810 #17 May 30 2025 03:31:57 %S A200810 3,3,5,3,7,3,3,3,11,3,13,3,3,5,17,3,19,3,3,3,23,3,3,3,3,3,29,3,31,3,3, %T A200810 3,3,3,37,3,3,3,41,3,43,3,3,3,47,3,3,3,3,3,53,3,3,3,3,3,59,3,61,3,3,7, %U A200810 3,3,67,3,3,3,71,3,73,3,3,3,3,3,79,3,5,3,83 %N A200810 Iterate k -> d(k) until an odd prime is reached. %C A200810 Csajbók and Kasza call this "lasttau(n)". Imre Kátai asks for its asymptotic behavior. %H A200810 Charles R Greathouse IV, <a href="/A200810/b200810.txt">Table of n, a(n) for n = 3..10000</a> %H A200810 Tímea Csajbók and János Kasza, <a href="https://doi.org/10.71352/ac.35.083">Iterating the tau-function</a>, Annales Univ. Sci. Budapest., Sec. Math. 35 (2011), pp. 83-93. %o A200810 (PARI) a(n)=while(!isprime(n),n=numdiv(n));n \\ _Charles R Greathouse IV_, Nov 23 2011 %Y A200810 Cf. A200811, A200815. %K A200810 nonn %O A200810 3,1 %A A200810 _Charles R Greathouse IV_, Nov 23 2011