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A087278
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Distance to nearest square is not greater than 1.
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1
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0, 1, 2, 3, 4, 5, 8, 9, 10, 15, 16, 17, 24, 25, 26, 35, 36, 37, 48, 49, 50, 63, 64, 65, 80, 81, 82, 99, 100, 101, 120, 121, 122, 143, 144, 145, 168, 169, 170, 195, 196, 197, 224, 225, 226, 255, 256, 257, 288, 289, 290, 323, 324, 325, 360, 361, 362, 399, 400, 401
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Union of A005563, A000290 and A002522:
a(3*k) = (k+1)^2 - 1 = A005563(k+1);
a(3*k+1) = (k+1)^2 = A000290(k+1);
a(3*k+2) = (k+1)^2 + 1 = A002522(k+1);
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FORMULA
| a(n) = floor(n/3)*(floor(n/3) + 2) + n mod 3.
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MATHEMATICA
| dnsQ[n_]:=Module[{x=Floor[Sqrt[n]]}, Min[n-x^2, (x+1)^2-n]<=1]; Select[Range[0, 450], dnsQ] (* From Harvey P. Dale, May 25 2011 *)
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CROSSREFS
| Cf. A002264, A010872, A087279.
Sequence in context: A102471 A094566 A190018 * A054219 A116214 A161389
Adjacent sequences: A087275 A087276 A087277 * A087279 A087280 A087281
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 28 2003
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