a(n) is the largest number m such that m = pi(n*m).

Terms

a(0) =4a(1) =11a(2) =30a(3) =72a(4) =189a(5) =442a(6) =1059a(7) =2700a(8) =6472a(9) =15927a(10) =40121a(11) =100363a(12) =251761a(13) =637340a(14) =1617174a(15) =4124705a(16) =10553853a(17) =27067277a(18) =69709965a(19) =179993173a(20) =465769838a(21) =1208198861a(22) =3140421934a(23) =8179002208a(24) =21338685406a(25) =55762149115a(26) =145935689393