Convolution of A023531 and A001950.

Terms

a(0) =0a(1) =2a(2) =5a(3) =7a(4) =12a(5) =18a(6) =22a(7) =28a(8) =35a(9) =43a(10) =51a(11) =58a(12) =67a(13) =77a(14) =87a(15) =97a(16) =108a(17) =119a(18) =129a(19) =141a(20) =155a(21) =167a(22) =181a(23) =194a(24) =206a(25) =221a(26) =235a(27) =251a(28) =266a(29) =282