Number of primitive (period n) periodic palindromes using a maximum of six different symbols.

A056497

Number of primitive (period n) periodic palindromes using a maximum of six different symbols.

Terms

    a(0) =6a(1) =15a(2) =30a(3) =105a(4) =210a(5) =705a(6) =1290a(7) =4410a(8) =7740a(9) =26985a(10) =46650a(11) =162435a(12) =279930a(13) =978465a(14) =1679370a(15) =5874120a(16) =10077690a(17) =35263440a(18) =60466170a(19) =211604295a(20) =362795730a(21) =1269743025a(22) =2176782330a(23) =7618570470a(24) =13060693800

External references