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 A047892 #19 Feb 16 2024 10:10:17 %S A047892 2,4,16,112,448,7168,157696,5361664,166211584,5651193856,276908498944, %T A047892 19383594926080,1298700860047360,79220752462888960, %U A047892 6733763959345561600,592571228422409420800,45035413360103115980800 %N A047892 a(1) = 2; for n > 0, a(n+1) = a(n) * sum of digits of a(n). %C A047892 a(n) mod 9 = A010712(n-1) for n > 1. - _Reinhard Zumkeller_, Sep 23 2007 %H A047892 Reinhard Zumkeller, <a href="/A047892/b047892.txt">Table of n, a(n) for n = 1..250</a> %F A047892 a(n+1) = A057147(a(n)). - _Reinhard Zumkeller_, Mar 19 2014 %t A047892 NestList[# Total[IntegerDigits[#]]&,2,20] (* _Harvey P. Dale_, Jul 18 2011 *) %o A047892 (Haskell) %o A047892 a047892 n = a047892_list !! (n-1) %o A047892 a047892_list = iterate a057147 2 -- _Reinhard Zumkeller_, Mar 19 2014 %Y A047892 Cf. A004207. %Y A047892 Cf. A007953. %Y A047892 Cf. A047912 (start=3), A047897 (start=5), A047898 (start=6), A047899 (start=7), A047900 (start=8), A047901 (start=9), A047902 (start=11). %K A047892 nonn,base,easy,nice %O A047892 1,1 %A A047892 Miklos SZABO (mike(AT)ludens.elte.hu) %E A047892 Offset changed by _Reinhard Zumkeller_, Mar 19 2014