A047912 a(1) = 3; for n > 0, a(n+1) = a(n) * sum of digits of a(n).

3, 9, 81, 729, 13122, 118098, 3188646, 114791256, 4132485216, 148769467776, 10711401679872, 578415690713088, 41645929731342336, 2998506940656648192, 296852187125008171008, 24045027157125661851648

Offset: 1

Author

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

Keywords

• easy
• nice
• nonn
• base

Comments

Apart from the first term, the same as A047901. - R. J. Mathar, Oct 18 2008

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..250

Crossrefs

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

Programs

Haskell

a047912 n = a047912_list !! (n-1)
a047912_list = iterate a057147 3  -- Reinhard Zumkeller, Mar 19 2014

Mathematica

NestList[# Total[IntegerDigits[#]]&,3,20]  (* Harvey P. Dale, Mar 21 2011 *)

Formula

a(n+1) = A057147(a(n)). - Reinhard Zumkeller, Mar 19 2014