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A242401
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Numbers that are neither triangular nor square.
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4
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2, 5, 7, 8, 11, 12, 13, 14, 17, 18, 19, 20, 22, 23, 24, 26, 27, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 65, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79, 80, 82, 83, 84
(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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FORMULA
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EXAMPLE
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6 is not a term because it's triangular;
9 is not a term because it's square.
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MATHEMATICA
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With[{nn=90}, Complement[Range[nn], Range[Floor[Sqrt[nn]]]^2, Accumulate[ Range[ Floor[(Sqrt[1+8nn]-1)/2]]]]] (* Harvey P. Dale, May 03 2022 *)
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PROG
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(Sage)
[x for x in [1..100] if not(is_square(x)) and not(is_triangular_number(x))] # Tom Edgar, May 13 2014
(Haskell)
a242401 n = a242401_list !! (n-1)
a242401_list = filter ((== 0) . a010054) a000037_list
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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