Convolution of natural numbers >= 2 and A023531.

Terms

a(0) =0a(1) =2a(2) =3a(3) =4a(4) =7a(5) =9a(6) =11a(7) =13a(8) =17a(9) =20a(10) =23a(11) =26a(12) =29a(13) =34a(14) =38a(15) =42a(16) =46a(17) =50a(18) =54a(19) =60a(20) =65a(21) =70a(22) =75a(23) =80a(24) =85a(25) =90a(26) =97a(27) =103a(28) =109a(29) =115