Squares of odd tetrahedral numbers.

Terms

a(0) =1a(1) =1225a(2) =27225a(3) =207025a(4) =938961a(5) =3136441a(6) =8555625a(7) =20205025a(8) =42837025a(9) =83521321a(10) =152300281a(11) =262926225a(12) =433680625a(13) =688275225a(14) =1056835081a(15) =1576963521a(16) =2294889025a(17) =3266694025a(18) =4559625625a(19) =6253488241a(20) =8442118161a(21) =11234940025a(22) =14758605225a(23) =19158712225a(24) =24601608801