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A214412
Numbers that can't be expressed as the sum of a Fibonacci number and a square of a positive integer.
1
0, 8, 13, 15, 20, 23, 31, 32, 34, 40, 42, 45, 47, 48, 53, 55, 58, 60, 61, 63, 68, 73, 74, 75, 76, 78, 79, 87, 88, 92, 95, 96, 97, 99, 106, 107, 109, 110, 111, 112, 116, 117, 118, 120, 127, 128, 130, 131, 132, 133, 135, 137, 139, 140, 141, 143, 150, 151, 154, 156
OFFSET
1,2
COMMENTS
0 is considered to be a Fibonacci number.
MAPLE
q:= proc(n) local f, g; f, g:= 0, 1;
do if f>=n then return true
elif issqr(n-f) then return false
else f, g:= g, f+g
fi od
end:
select(q, [$0..200])[]; # Alois P. Heinz, May 22 2021
MATHEMATICA
nn = 156; sq = Range[Sqrt[nn]]^2; fb = {}; i = 0; While[f = Fibonacci[i]; f < nn, i++; AppendTo[fb, f]]; fb = Union[fb]; Complement[Range[0, nn], Union[Flatten[Outer[Plus, sq, fb]]]] (* T. D. Noe, Jul 31 2012 *)
PROG
(Python)
prpr = 0
prev = 1
fib = [0]*100
for n in range(100):
fib[n] = prpr
curr = prpr+prev
prpr = prev
prev = curr
#print fib[n]
for n in range(777):
i = 1
yes = 0
while i*i<=n:
r = n - i*i
if r in fib:
yes = 1
break
i += 1
if yes==0:
print n,
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alex Ratushnyak, Jul 16 2012
STATUS
approved