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(1)已知(1－2x)7＝a0＋a1x＋a2x2＋…＋a7x7，那么a1＋a2＋…＋a7＝________．
(2)若(x2＋x－1)n＝a0＋a1(x－1)＋a2(x－1)2＋…＋a2n(x－1)2n，则a0＋a1＋a2＋…＋a2n＝________．
(3)(x2－2x＋3)n＝a0＋a1x＋a2x2＋…＋a2n－1x2n－1＋a2nx2n，则a0＋a2＋a4＋a2n－2＋a2n＝________．