Maximal term in Collatz-iteration started at -1+2^n.

Terms

a(0) =1a(1) =16a(2) =52a(3) =160a(4) =9232a(5) =9232a(6) =4372a(7) =13120a(8) =39364a(9) =118096a(10) =1276936a(11) =1276936a(12) =6810136a(13) =9565936a(14) =28697812a(15) =86093440a(16) =1570824736a(17) =1570824736a(18) =2324522932a(19) =6973568800a(20) =20920706404a(21) =62762119216a(22) =188286357652a(23) =564859072960