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A271184
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Löschian numbers (A003136) of the form k^2+1.
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1
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1, 37, 325, 577, 1297, 2917, 3601, 4357, 7057, 8101, 9217, 14401, 15877, 22501, 24337, 28225, 32401, 41617, 44101, 46657, 57601, 60517, 69697, 72901, 79525, 86437, 90001, 93637, 108901, 133957, 147457, 156817, 176401, 197137, 202501, 219025, 224677, 236197, 291601, 298117, 318097
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OFFSET
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1,2
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COMMENTS
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Corresponding values of k are 0, 6, 18, 24, 36, 54, 60, 66, 84, 90, 96, 120, 126, 150, 156, 168, 180, 204, 210, 216, 240, 246, 264, 270, 282, 294, 300, 306, ...
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LINKS
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EXAMPLE
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37 is a term because 37 = 6^2 + 1 = 4^2 + 4*3 + 3^2.
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MATHEMATICA
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Select[Range[10^6], And[IntegerQ@Sqrt[# - 1], Resolve[Exists[{x, y}, Reduce[# == x^2 + x y + y^2, {x, y}, Integers]]]] &] (* Michael De Vlieger, Apr 01 2016 *)
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PROG
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(PARI) is(n) = #bnfisintnorm(bnfinit(z^2+z+1), n);
for(k=0, 2000, if(is(n=k^2+1), print1(n, ", ")));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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