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A115177
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Positive numbers that are not the sum of a triangular number, a nonnegative cube and a positive Fibonacci number.
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9
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690, 861, 915, 929, 1201, 1319, 1451, 1538, 1578, 1803, 1965, 2104, 2427, 2532, 2573, 2671, 2680, 2734, 2769, 2965, 3001, 3154, 3175, 3255, 3259, 3260, 3336, 3434, 3476, 3603, 3628, 3670, 3805, 3840, 3847, 3898, 3903, 3953, 4050, 4128
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OFFSET
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1,1
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COMMENTS
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There are 225943534 such numbers up to 10^9, the last one in this range being 999999997.
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LINKS
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MAPLE
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N:=10000: # to get all terms <= N
T:= [seq(t*(t+1)/2, t=0..floor((sqrt(1+8*N)-1)/2))]:
C:= [seq(t^3, t=0..floor(N^(1/3)))]:
F:= [seq(combinat:-fibonacci(t), t=1..floor(log[(sqrt(5)+1)/2](N*sqrt(5))))]:
CF:= select(`<=`, {seq(seq(c+f, c=C), f=F)}, N):
sort(convert({$1..N} minus {seq(seq(t+cf, t=T), cf=CF)}, list)); # Robert Israel, Mar 08 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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