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A111458
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Numbers that cannot be represented as the sum of at most three Fibonacci numbers (with repetitions allowed).
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4
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33, 46, 51, 53, 54, 67, 72, 74, 75, 80, 82, 83, 85, 86, 87, 88, 101, 106, 108, 109, 114, 116, 117, 119, 120, 121, 122, 127, 129, 130, 132, 133, 134, 135, 137, 138, 139, 140, 141, 142, 143, 156, 161, 163, 164, 169, 171, 172
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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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EXAMPLE
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33 is neither a Fibonacci number nor can be written as the sum of two or three Fibonacci numbers.
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MAPLE
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isA111458 := proc(n) # returns true if n is in the sequence
local xi, yi, x, y, z ;
for xi from 0 do
if 3*x > n then
return true;
end if;
for yi from xi do
if x+2*y > n then
break;
else
z := n-x-y ;
if isA000045(z) then # see isFib in A000045
return false;
end if;
end if;
end do:
end do:
end proc:
option remember;
local a;
if n = 0 then
-1;
else
for a from procname(n-1)+1 do
if isA111458(a) then
return a;
end if;
end do:
end if;
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MATHEMATICA
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FibQ[n_] := IntegerQ[Sqrt[5n^2+4]] || IntegerQ[Sqrt[5n^2-4]];
P[n_] := IntegerPartitions[n, 3, Select[Range[n], FibQ]];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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