Convolution of natural numbers >= 2 and A023532.

Terms

a(0) =2a(1) =3a(2) =6a(3) =10a(4) =13a(5) =18a(6) =24a(7) =31a(8) =37a(9) =45a(10) =54a(11) =64a(12) =75a(13) =85a(14) =97a(15) =110a(16) =124a(17) =139a(18) =155a(19) =170a(20) =187a(21) =205a(22) =224a(23) =244a(24) =265a(25) =287a(26) =308a(27) =331a(28) =355a(29) =380