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A188112
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Integers of the form x^2+xy+2y^2,with x and y nonnegative, with repetitions.
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1
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0, 1, 2, 4, 4, 8, 8, 9, 11, 14, 16, 16, 18, 22, 22, 23, 25, 28, 32, 32, 32, 36, 36, 37, 43, 44, 44, 46, 49, 50, 53, 56, 56, 58, 58, 64, 64, 64, 71, 72, 72, 74, 74, 77, 79, 81, 86, 88, 88, 88, 92, 92, 98, 99, 100, 100, 106, 106, 107, 109, 112, 112, 116, 116, 121, 126, 127
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OFFSET
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1,3
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COMMENTS
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Primes appear only once.
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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EXAMPLE
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{n,x,y}: {0,0,0},...,{4,1,1},{4,2,0},{8,0,2},{8,2,1},...,{11,1,2},{14,3,1}.
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MATHEMATICA
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f[upto_]:=Module[{max=Floor[Sqrt[upto]], s}, s=Sort[First[#]^2+ Times@@#+2Last[#]^2&/@Tuples[Range[0, max], {2}]]; Select[s, #<=upto&]]; f[150] (* Harvey P. Dale, Mar 28 2011 *)
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CROSSREFS
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Cf. A106856, primes of the form x^2+xy+2y^2, with x and y nonnegative.
Sequence in context: A207872 A140513 A265322 * A333194 A349131 A166632
Adjacent sequences: A188109 A188110 A188111 * A188113 A188114 A188115
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KEYWORD
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nonn,easy
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AUTHOR
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Zak Seidov, Mar 21 2011
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STATUS
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approved
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