Numbers taking exactly 21 steps to reach 15 in A086793.

Terms

a(0) =71820a(1) =103950a(2) =127764a(3) =135660a(4) =141360a(5) =161460a(6) =173250a(7) =183744a(8) =193284a(9) =203580a(10) =206712a(11) =209440a(12) =214830a(13) =217620a(14) =221760a(15) =223020a(16) =223860a(17) =234432a(18) =243540a(19) =244440a(20) =246330a(21) =247752a(22) =256680a(23) =263160a(24) =264180a(25) =265200a(26) =280368a(27) =281160a(28) =286380a(29) =287712