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A047897 a(1) = 5; for n > 0, a(n+1) = a(n) * sum of digits of a(n). 11
5, 25, 175, 2275, 36400, 473200, 7571200, 166566400, 5663257600, 226530304000, 5663257600000, 226530304000000, 5663257600000000, 226530304000000000, 5663257600000000000, 226530304000000000000, 5663257600000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

After a(9), every second element has the same beginning. a(11+2k) = 40 * a(10+2k) = 40 * 25 * a(9+2k).

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:=5; 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[#]]&, 5, 20] (* Harvey P. Dale, Jan 25 2014 *)

PROG

(Haskell)

a047897 n = a047897_list !! (n-1)

a047897_list = iterate a057147 5  -- Reinhard Zumkeller, Mar 19 2014

CROSSREFS

Cf. A047892 (start=2), A047912 (start=3), A047898 (start=6), A047899 (start=7), A047900 (start=8), A047901 (start=9), A047902 (start=11).

Sequence in context: A258369 A137383 A049035 * A204461 A121144 A096684

Adjacent sequences:  A047894 A047895 A047896 * A047898 A047899 A047900

KEYWORD

easy,nonn,base

AUTHOR

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

STATUS

approved

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Last modified June 20 04:43 EDT 2021. Contains 345157 sequences. (Running on oeis4.)