Convolution of the even-indexed triangular numbers (A014105) and the squares (A000290).

Terms

a(0) =0a(1) =0a(2) =3a(3) =22a(4) =88a(5) =258a(6) =623a(7) =1316a(8) =2520a(9) =4476a(10) =7491a(11) =11946a(12) =18304a(13) =27118a(14) =39039a(15) =54824a(16) =75344a(17) =101592a(18) =134691a(19) =175902a(20) =226632a(21) =288442a(22) =363055a(23) =452364a(24) =558440a(25) =683540a(26) =830115a(27) =1000818a(28) =1198512a(29) =1426278