Partial sums of partial sums of (A001840 interleaved with zeros).

Terms

a(0) =1a(1) =2a(2) =5a(3) =8a(4) =14a(5) =20a(6) =31a(7) =42a(8) =60a(9) =78a(10) =105a(11) =132a(12) =171a(13) =210a(14) =264a(15) =318a(16) =390a(17) =462a(18) =556a(19) =650a(20) =770a(21) =890a(22) =1040a(23) =1190a(24) =1375a(25) =1560a(26) =1785a(27) =2010a(28) =2280a(29) =2550