Odd values arising in A066820.

Terms

a(0) =1a(1) =25a(2) =1105a(3) =5095a(4) =8925a(5) =54549a(6) =218295a(7) =478423a(8) =939575a(9) =1475901a(10) =5047977a(11) =7635033a(12) =11213895a(13) =20680985a(14) =16776123a(15) =23599303a(16) =19371925a(17) =28569569a(18) =31983147a(19) =33984405a(20) =30885975a(21) =38189799a(22) =42059765a(23) =35086905a(24) =49400043a(25) =45711639