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 A047897 #19 Feb 17 2024 10:34:23 %S A047897 5,25,175,2275,36400,473200,7571200,166566400,5663257600,226530304000, %T A047897 5663257600000,226530304000000,5663257600000000,226530304000000000, %U A047897 5663257600000000000,226530304000000000000,5663257600000000000000 %N A047897 a(1) = 5; for n > 0, a(n+1) = a(n) * sum of digits of a(n). %C A047897 After a(9), every second element has the same beginning. a(11+2k) = 40 * a(10+2k) = 40 * 25 * a(9+2k). %H A047897 Reinhard Zumkeller, <a href="/A047897/b047897.txt">Table of n, a(n) for n = 1..250</a> %F A047897 a(n+1) = A057147(a(n)). - _Reinhard Zumkeller_, Mar 19 2014 %t A047897 NestList[#*Total[IntegerDigits[#]]&,5,20] (* _Harvey P. Dale_, Jan 25 2014 *) %o A047897 (Haskell) %o A047897 a047897 n = a047897_list !! (n-1) %o A047897 a047897_list = iterate a057147 5 -- _Reinhard Zumkeller_, Mar 19 2014 %Y A047897 Cf. A047892 (start=2), A047912 (start=3), A047898 (start=6), A047899 (start=7), A047900 (start=8), A047901 (start=9), A047902 (start=11). %K A047897 easy,nonn,base %O A047897 1,1 %A A047897 Miklos SZABO (mike(AT)ludens.elte.hu)