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A259851
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Numbers x such that x = concat(a, b) and a’ * b’ = x, where a’ and b’ are the arithmetic derivatives of a and b.
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1
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48, 448, 708, 6560, 279207, 350400, 1050000, 1837500, 2480128, 2600000, 4687500, 7562500, 10762500, 25712000, 27337500, 28650000, 34912500, 57450000, 62568960, 65312500, 65871440, 106505392, 153456128, 213939328, 245600000, 258332000, 281600000, 285650000
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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Lars Blomberg, Table of n, a(n) for n = 1..58
Michel Marcus, x = a' * b'
OEIS Wiki, Arithmetic derivative.
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EXAMPLE
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Consider 48 as concat(4,8). We have 4’ = 4, 8’ = 12 and 4 * 12 = 48.
Consider 448 as concat(4,48). We have 4’ = 4, 48’ = 112 and 4 * 112 = 448.
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MAPLE
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isA259851 := proc(x)
local i, a, b;
for i from 1 to ilog10(n) do
a:=floor(n/10^i);
b:=n-a*10^i;
if A003415(a)*A003415(b) = x then
return true;
end if;
end do:
false ;
end proc:
for n from 1 do
if isA259851(n) then
print(n) ;
end if;
end do: # R. J. Mathar, Jul 08 2015
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CROSSREFS
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Cf. A003415.
Sequence in context: A190416 A231342 A192828 * A223419 A333671 A287762
Adjacent sequences: A259848 A259849 A259850 * A259852 A259853 A259854
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KEYWORD
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nonn,base
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AUTHOR
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Paolo P. Lava, Jul 07 2015
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EXTENSIONS
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More terms from Lars Blomberg, Oct 03 2015
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STATUS
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approved
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