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A047892 a(1) = 2; for n > 0, a(n+1) = a(n) * sum of digits of a(n). 15
2, 4, 16, 112, 448, 7168, 157696, 5361664, 166211584, 5651193856, 276908498944, 19383594926080, 1298700860047360, 79220752462888960, 6733763959345561600, 592571228422409420800, 45035413360103115980800 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

FORMULA

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

MAPLE

P:=proc(n) local a, i, k, w; a:=2; print(a); for i from 1 by 1 to n do w:=0; k:=a; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; a:=a*w; print(a); od; end: P(1000); # Paolo P. Lava, Apr 27 2007

MATHEMATICA

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

PROG

(Haskell)

a047892 n = a047892_list !! (n-1)

a047892_list = iterate a057147 2  -- Reinhard Zumkeller, Mar 19 2014

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).

Sequence in context: A135249 A318154 A110365 * A275911 A334351 A009200

Adjacent sequences:  A047889 A047890 A047891 * A047893 A047894 A047895

KEYWORD

nonn,base,easy,nice

AUTHOR

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

EXTENSIONS

Offset changed by Reinhard Zumkeller, Mar 19 2014

STATUS

approved

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Last modified June 22 21:29 EDT 2021. Contains 345393 sequences. (Running on oeis4.)