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A280682
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Integers m such that floor(sqrt(m)) is even.
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1
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0, 4, 5, 6, 7, 8, 16, 17, 18, 19, 20, 21, 22, 23, 24, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120
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OFFSET
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1,2
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COMMENTS
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Also integers m such that Sum_{k=1..m} floor(k/m) is even (cf. A006218). See the Mathematical Reflections link.
This sequence is composed of blocks of 1,5,9,13,... (A016813:4n+1) consecutive terms, separated by 3,7,11,15,... (A004767:4n+3) consecutive terms.
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LINKS
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EXAMPLE
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3 whose sqrt is 1.732... does not belong to this sequence.
5 whose sqrt is 2.236... belongs to this sequence.
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PROG
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(PARI) isok(n) = (sqrtint(n) % 2) == 0; \\ Michel Marcus, Jan 07 2017
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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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