solutions of T^15 ...:
r: 3.74112075663244020631, r/4: 0.935280189158110051577; 4R: 6.51374300244120148928, R: 1.62843575061030037232
r: 3.90610742813799013941, r/4: 0.976526857034497534852; 4R: 7.44546038387880352228, R: 1.86136509596970088057
r: 3.99029618557765366727, r/4: 0.997574046394413416817; 4R: 7.94187127748026534030, R: 1.98546781937006633508