Squares of odd hexagonal pyramidal numbers.

Terms

a(0) =1a(1) =49a(2) =9025a(3) =25921a(4) =275625a(5) =511225a(6) =2393209a(7) =3705625a(8) =11675889a(9) =16378209a(10) =40844881a(11) =53831569a(12) =115025625a(13) =145226601a(14) =278055625a(15) =340218025a(16) =600103009a(17) =716900625a(18) =1186595809a(19) =1391066209a(20) =2188461961a(21) =2526771289a(22) =3813680025