A047892 a(1) = 2; for n > 0, a(n+1) = a(n) * sum of digits of a(n).

2, 4, 16, 112, 448, 7168, 157696, 5361664, 166211584, 5651193856, 276908498944, 19383594926080, 1298700860047360, 79220752462888960, 6733763959345561600, 592571228422409420800, 45035413360103115980800

Offset: 1

Author

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

Keywords

• nonn
• base
• easy
• nice

Comments

a(n) mod 9 = A010712(n-1) for n > 1. - Reinhard Zumkeller, Sep 23 2007

Links

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

Crossrefs

Cf. A004207.

Cf. A007953.

Cf. A047912 (start=3), A047897 (start=5), A047898 (start=6), A047899 (start=7), A047900 (start=8), A047901 (start=9), A047902 (start=11).

Programs

Haskell

a047892 n = a047892_list !! (n-1)
a047892_list = iterate a057147 2  -- Reinhard Zumkeller, Mar 19 2014

Mathematica

NestList[# Total[IntegerDigits[#]]&,2,20] (* Harvey P. Dale, Jul 18 2011 *)

Formula

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

Extensions

Offset changed by Reinhard Zumkeller, Mar 19 2014