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A047900 a(1) = 8; for n > 0, a(n+1) = a(n) * sum of digits of a(n). 11
8, 64, 640, 6400, 64000, 640000, 6400000, 64000000, 640000000, 6400000000, 64000000000, 640000000000, 6400000000000, 64000000000000, 640000000000000, 6400000000000000, 64000000000000000, 640000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

After the 2nd element, every element has the same beginning.

a(3+k) = 10 * a(2+k).

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:=8; 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[#]]&, 8, 20] (* or *) Join[{8}, NestList[ 10#&, 64, 20]] (* Harvey P. Dale, Jul 03 2020 *)

PROG

(Haskell)

a047900 n = a047900_list !! (n-1)

a047900_list = iterate a057147 8  -- Reinhard Zumkeller, Mar 19 2014

CROSSREFS

Cf. A047892 (start=2), A047912 (start=3), A047897 (start=5), A047898 (start=6), A047899 (start=7), A047901 (start=9), A047902 (start=11).

Sequence in context: A344252 A199567 A213336 * A204212 A238724 A318640

Adjacent sequences:  A047897 A047898 A047899 * A047901 A047902 A047903

KEYWORD

easy,nonn,base

AUTHOR

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

STATUS

approved

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Last modified June 22 03:25 EDT 2021. Contains 345367 sequences. (Running on oeis4.)