Sum over all partitions of n of the number of distinct parts i of multiplicity i - 1.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =1a(5) =2a(6) =4a(7) =5a(8) =8a(9) =10a(10) =15a(11) =20a(12) =29a(13) =37a(14) =52a(15) =67a(16) =89a(17) =115a(18) =152a(19) =192a(20) =251a(21) =316a(22) =405a(23) =508a(24) =644a(25) =799a(26) =1006a(27) =1243a(28) =1546a(29) =1901