For 2,7, - 6,19, - 22,39 The tenth item is [], and the nth item is [] I've become stupid recently. I can't find out who can help me=-=

For 2,7, - 6,19, - 22,39 The tenth item is [], and the nth item is [] I've become stupid recently. I can't find out who can help me=-=

The tenth is - 78 123