Where t5(n) is the n-th Pentanacci number as defined by:
a(0)=0, a(1)=0, a(2)=0, a(3)=0, a(4)=1; a(n)=a(n-1)+a(n-2)+a(n-3)+a(n-4)

t5(71807) = 1220923845...6965114497
t5(155957) = 1503522970...5121042449


Verified PRP by pfgw.

To be completed...