Number of parts, counted without multiplicity, in all compositions of n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =13a(5) =30a(6) =66a(7) =144a(8) =308a(9) =655a(10) =1380a(11) =2891a(12) =6024a(13) =12500a(14) =25844a(15) =53274a(16) =109530a(17) =224690a(18) =460033a(19) =940276a(20) =1918979a(21) =3911186a(22) =7962194a(23) =16191875a(24) =32896364a(25) =66776727a(26) =135445212a(27) =274532607a(28) =556086916a(29) =1125727954