Convolution square of A003114.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =7a(5) =10a(6) =15a(7) =20a(8) =28a(9) =38a(10) =52a(11) =68a(12) =91a(13) =118a(14) =153a(15) =196a(16) =252a(17) =318a(18) =403a(19) =504a(20) =632a(21) =784a(22) =973a(23) =1196a(24) =1473a(25) =1800a(26) =2198a(27) =2668a(28) =3238a(29) =3908