A034168 Disjoint discriminants (one form per genus) of type 2 (doubled).
2, 6, 10, 22, 30, 42, 58, 70, 78, 102, 130, 190, 210, 330, 462
Offset: 1
References
- J. M. Borwein and P. B. Borwein, Pi and the AGM, page 293.
- L. E. Dickson, Introduction to the theory of numbers, Dover, NY, 1929.
Links
- J. M. Borwein, Adventures with the OEIS: Five sequences Tony may like, Guttmann 70th [Birthday] Meeting, 2015, revised May 2016.
- J. M. Borwein, Adventures with the OEIS: Five sequences Tony may like, Guttmann 70th [Birthday] Meeting, 2015, revised May 2016. [Cached copy, with permission]
- J. Borwein and K.-K. S. Choi, On the representations of xy+yz+zx, Experimental Mathematics, 9 (2000), 153-158.
- Experimental Mathematics, Home Page
Programs
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Mathematica
noSol = {}; Do[lim = Ceiling[(n-2)/3]; found = False; Do[If[n > a*b && Mod[n - a*b, a+b] == 0 && Quotient[n - a*b, a+b] > b, found = True; Break[]], {a, 1, lim-1}, {b, a+1, lim}]; If[!found, AppendTo[noSol, n]], {n, 1000}]; Select[noSol, EvenQ[#] && SquareFreeQ[#]&] (* Jean-François Alcover, Jul 21 2022, after T. D. Noe in A000926 *) -
PARI
ok(n)={n%4==2 && issquarefree(n) && !select(t->t<>2, quadclassunit(-4*n).cyc)} \\ Andrew Howroyd, Jun 09 2018
Comments