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Search: id:A135198
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| A135198 |
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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=13. |
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+0
17
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| 780, 1890, 4620, 5040, 7800, 12360, 18900, 20610, 22950
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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780^1=780 is multiple of Sum_digits(780)=15
780^2=608400 is multiple of Sum_digits(608400)=18
etc. till
780^13=39557590922648009090580480000000000000 is a multiple of Sum_digits(39557590922648009090580480000000000000)=117
while
780^14=30854920919665447090652774400000000000000 is not multiple of Sum_digits(30854920919665447090652774400000000000000)=126
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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(25000, 13);
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CROSSREFS
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Cf. A135186, A135187, A135188, A135189, A135190, A135191, A135192, A135193, A135194, A135195, A135196, A135197, A135199, A135200, A135201, A135202.
Sequence in context: A043384 A008746 A147547 this_sequence A139400 A115467 A020231
Adjacent sequences: A135195 A135196 A135197 this_sequence A135199 A135200 A135201
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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 23 2007
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