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Search: id:A135188
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| A135188 |
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Numbers n that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (n raised to k+1 must not be a multiple). Case k=3. |
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+0
17
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| 2, 20, 72, 80, 84, 108, 112, 156, 198, 200, 216, 324, 351, 378, 504, 522, 558, 612, 684, 738, 800, 902, 918, 936, 972
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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20^1=20 -> Sum_digits(20)=2 and 20 is a multiple of 2.
20^2=400 -> Sum_digits(400)=4 and 400 is a multiple of 4.
20^3=8000 -> Sum_digits(8000)=8 and 8000 is a multiple of 8.
20^4=160000 -> Sum_digits(160000)=7 and 160000 is not a multiple of 7.
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MAPLE
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readlib(log10); P:=proc(n, m) local a, i, k, w, x, ok; for i from 1 by 1 to n do a:=simplify(log10(i)); if not (trunc(a)=a) then ok:=1; x:=1; while ok=1 do w:=0; k:=i^x; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; if trunc(i^x/w)=i^x/w then x:=x+1; else if x-1=m then print(i); fi; ok:=0; fi; od; fi; od; end: P(2000, 3);
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CROSSREFS
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Cf. A135186, A135187, A135189, A135190, A135191, A135192, A135193, A135194, A135195, A135196, A135197, A135198, A135199, A135200, A135201, A135202.
Sequence in context: A001504 A136905 A003283 this_sequence A161007 A098077 A063663
Adjacent sequences: A135185 A135186 A135187 this_sequence A135189 A135190 A135191
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KEYWORD
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easy,nonn,base
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Nov 22 2007
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