1/24 the number of colorings of a 3 X 3 octagonal array with n colors.

Terms

a(0) =3a(1) =280a(2) =5265a(3) =47040a(4) =271250a(5) =1170288a(6) =4105710a(7) =12334080a(8) =32837805a(9) =79365000a(10) =177200023a(11) =370319040a(12) =731732820a(13) =1377981920a(14) =2488927500a(15) =4334174208a(16) =7307669895a(17) =11972250360a(18) =19116135885a(19) =29823640000a(20) =45562619718a(21) =68291480400a(22) =100588847450a(23) =145809331200