Starting with polynomial:
P : 65536*t^16 - 3932160*t^14 + 89456640*t^12 - 984023040*t^10 + 5535129600*t^8 - 15498362880*t^6 + 19372953600*t^4 - 8302694400*t^2 + 518918400
Extension levels are: 16 23
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Trying to find an order 23 Kronrod extension for:
P1 : 65536*t^16 - 3932160*t^14 + 89456640*t^12 - 984023040*t^10 + 5535129600*t^8 - 15498362880*t^6 + 19372953600*t^4 - 8302694400*t^2 + 518918400
Solvable: 1
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Ending with final polynomial:
P : 65536*t^39 - 8688664244074741760/517583353637*t^37 + 990262000761694863360/517583353637*t^35 - 9508323843336329256960/73940479091*t^33 + 421201458824633375539200/73940479091*t^31 - 13020231660780715306721280/73940479091*t^29 + 290117549060584583592038400/73940479091*t^27 - 4746980766094138315089561600/73940479091*t^25 + 57579864600285727289739072000/73940479091*t^23 - 519160629521416220138132640000/73940479091*t^21 + 3468607205454914311052787600000/73940479091*t^19 - 17022618682210577742963730920000/73940479091*t^17 + 60455882488038275870457071400000/73940479091*t^15 - 151935116226911540588791826100000/73940479091*t^13 + 261511778903513393054465716050000/73940479091*t^11 - 293592758641547278809747536685000/73940479091*t^9 + 198930385082023356722484470821875/73940479091*t^7 - 142422541931580126074411975296875/147880958182*t^5 + 42617326845917264694121427934375/295761916364*t^3 - 3785124500229339318122368171875/591523832728*t
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Computing nodes and weights
  current precision for roots: 53
  current precision for roots: 106
 current precision for weights: 53
Linear system for weights solvable: 0
  current precision for roots: 106
  current precision for roots: 212
 current precision for weights: 106
Linear system for weights solvable: 0
  current precision for roots: 212
  current precision for roots: 424
 current precision for weights: 212
Linear system for weights solvable: 1
Sufficient bits for target precision reached
Positive weights:   37 out of 39
Indefinite weights: 0 out of 39
Negative weights:   2 out of 39
Extension rule has valid weights: 0
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*** EXTENSION WITH INVALID WEIGHTS ***
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