Pyramidal centered square numbers.

Terms

a(0) =1a(1) =15a(2) =91a(3) =325a(4) =861a(5) =1891a(6) =3655a(7) =6441a(8) =10585a(9) =16471a(10) =24531a(11) =35245a(12) =49141a(13) =66795a(14) =88831a(15) =115921a(16) =148785a(17) =188191a(18) =234955a(19) =289941a(20) =354061a(21) =428275a(22) =513591a(23) =611065a(24) =721801a(25) =846951a(26) =987715a(27) =1145341a(28) =1321125a(29) =1516411