Number of palindromes using a maximum of five different symbols.

Terms

a(0) =1a(1) =5a(2) =5a(3) =25a(4) =25a(5) =125a(6) =125a(7) =625a(8) =625a(9) =3125a(10) =3125a(11) =15625a(12) =15625a(13) =78125a(14) =78125a(15) =390625a(16) =390625a(17) =1953125a(18) =1953125a(19) =9765625a(20) =9765625a(21) =48828125a(22) =48828125a(23) =244140625a(24) =244140625a(25) =1220703125a(26) =1220703125a(27) =6103515625a(28) =6103515625a(29) =30517578125