Number of primitive (aperiodic) palindromes using a maximum of five different symbols.

Terms

a(0) =5a(1) =0a(2) =20a(3) =20a(4) =120a(5) =100a(6) =620a(7) =600a(8) =3100a(9) =3000a(10) =15620a(11) =15480a(12) =78120a(13) =77500a(14) =390480a(15) =390000a(16) =1953120a(17) =1949900a(18) =9765620a(19) =9762480a(20) =48827480a(21) =48812500a(22) =244140620a(23) =244124400a(24) =1220703000a(25) =1220625000a(26) =6103512500a(27) =6103437480a(28) =30517578120a(29) =30517184400