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A257854
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a(n) = 2*n^4 - floor(2^(1/4)*n)^4.
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2
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0, 1, 16, 81, 256, 625, 191, 706, 1631, 3122, 5359, 721, 3056, 6497, 11296, 17729, 751, 7042, 15471, 26386, 40159, 57186, 11536, 28241, 48896, 73969, 103952, 14306, 43391, 78226, 119375, 167426, 12016, 58401, 112672, 175489, 247536, 226, 69647, 149426, 240319
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OFFSET
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0,3
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COMMENTS
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Is there a simple expression for a nontrivial lower bound for a(n)?
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LINKS
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EXAMPLE
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a(5) = 2*5^4 - floor(2^(1/4)*5)^4 = 2*625 - 5^4 = 625.
a(6) = 2*6^4 - floor(2^(1/4)*6)^4 = 2*1296 - 7^4 = 191.
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MATHEMATICA
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PROG
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(PARI) f(n, e=4, b=2)=n^e*b-floor(sqrtn(b, e)*n)^e
(Magma) [2*n^4 - Floor(2^(1/4)*n)^4: n in [0..50]]; // Vincenzo Librandi, May 29 2015
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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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