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 A276456 Integers n such that the Klein invariant J((-1+sqrt(-n))/2) is a rational number. 0
 1, 3, 7, 11, 19, 27, 43, 67, 163 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Probably sequence is finite and complete. This sequence looks very much like A003173, the Heegner numbers, except for two terms (add 2, remove 27). Is there a proof of this connection? - Luc Rousseau, Nov 30 2017 LINKS EXAMPLE a(1) = 1 because J((-1+sqrt(-1))/2) = 1; a(2) = 3 because J((-1+sqrt(-3))/2) = 0; a(3) = 7 because J((-1+sqrt(-7))/2) = -125/64; a(4) = 11 because J((-1+sqrt(-11))/2) = -512/27; a(5) = 19 because J((-1+sqrt(-19))/2) = -512; a(6) = 27 because J((-1+sqrt(-27))/2) = -64000/9; a(7) = 43 because J((-1+sqrt(-43))/2) = -512000; a(8) = 67 because J((-1+sqrt(-67))/2) = -85184000; a(9) = 163 because J((-1+sqrt(-163))/2) = -151931373056000. MATHEMATICA Rationalize[N[KleinInvariantJ[(-1+I Sqrt[{1, 3, 7, 11, 19, 27, 43, 67, 163}])/2], 100]] CROSSREFS Sequence in context: A181497 A292095 A265323 * A126254 A092102 A158722 Adjacent sequences:  A276453 A276454 A276455 * A276457 A276458 A276459 KEYWORD nonn AUTHOR Artur Jasinski, Sep 03 2016 STATUS approved

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Last modified May 12 22:49 EDT 2021. Contains 343829 sequences. (Running on oeis4.)