A047912 - OEIS

%I #20 Feb 18 2024 08:17:43

%S 3,9,81,729,13122,118098,3188646,114791256,4132485216,148769467776,

%T 10711401679872,578415690713088,41645929731342336,2998506940656648192,

%U 296852187125008171008,24045027157125661851648

%N a(1) = 3; for n > 0, a(n+1) = a(n) * sum of digits of a(n).

%C Apart from the first term, the same as A047901. - _R. J. Mathar_, Oct 18 2008

%H Reinhard Zumkeller, <a href="/A047912/b047912.txt">Table of n, a(n) for n = 1..250</a>

%F a(n+1) = A057147(a(n)). - _Reinhard Zumkeller_, Mar 19 2014

%t NestList[# Total[IntegerDigits[#]]&,3,20]  (* _Harvey P. Dale_, Mar 21 2011 *)

%o (Haskell)

%o a047912 n = a047912_list !! (n-1)

%o a047912_list = iterate a057147 3  -- _Reinhard Zumkeller_, Mar 19 2014

%Y Cf. A047892 (start=2), A047897 (start=5), A047898 (start=6), A047899 (start=7), A047900 (start=8), A047901 (start=9), A047902 (start=11).

%K easy,nice,nonn,base

%O 1,1

%A Miklos SZABO (mike(AT)ludens.elte.hu)