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

Terms

a(0) =6a(1) =0a(2) =30a(3) =30a(4) =210a(5) =180a(6) =1290a(7) =1260a(8) =7740a(9) =7560a(10) =46650a(11) =46410a(12) =279930a(13) =278640a(14) =1679370a(15) =1678320a(16) =10077690a(17) =10069740a(18) =60466170a(19) =60458370a(20) =362795730a(21) =362750400a(22) =2176782330a(23) =2176734420a(24) =13060693800a(25) =13060414080a(26) =78364156320a(27) =78363884130a(28) =470184984570a(29) =470183297220