Total number of parts of the second sort in all partitions of n into two sorts of parts.

Terms

a(0) =0a(1) =1a(2) =5a(3) =17a(4) =53a(5) =145a(6) =385a(7) =957a(8) =2333a(9) =5493a(10) =12741a(11) =28941a(12) =65049a(13) =144225a(14) =317229a(15) =691457a(16) =1497901a(17) =3224145a(18) =6906969a(19) =14726701a(20) =31282421a(21) =66211253a(22) =139720445a(23) =294007373a(24) =617154865a(25) =1292516577a(26) =2701451621a(27) =5635565761a(28) =11736442005a(29) =24403092657