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A135206
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Numbers n for which Sum_digits(n!) is a multiple of Sum_digits(n!!).
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2
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1, 2, 3, 11, 19, 28, 48, 64, 158, 164, 190, 308, 324
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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EXAMPLE
| 11!=11*10*9*8*7*6*5*4*3*2*1=39916800 -> (3+9+9+1+6+8+0+0)=36
11!!=11*9*7*5*3*1=10395 -> (1+0+3+9+5)=18
36/18=2
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MAPLE
| P:=proc(n) local i, j, k, w, x; for i from 1 by 1 to n do w:=0; k:=i!; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; x:=i; j:=i-2; while j >0 do x:=x*j; j:=j-2; od: k:=x; x:=0; while k>0 do x:=x+k-(trunc(k/10)*10); k:=trunc(k/10); od; if trunc(w/x)=w/x then print(i); fi; od; end: P(1000);
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CROSSREFS
| Cf. A004152, A120390, A108825, A129980, A131954, A131955, A135204, A135205.
Sequence in context: A025105 A095984 A172258 * A111802 A095282 A051071
Adjacent sequences: A135203 A135204 A135205 * A135207 A135208 A135209
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KEYWORD
| hard,nonn,base
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AUTHOR
| Paolo P. Lava (paoloplava(AT)gmail.com), Nov 30 2007
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