Number of pair-coverings with largest block size 3.

Terms

a(0) =1a(1) =4a(2) =6a(3) =7a(4) =7a(5) =12a(6) =12a(7) =19a(8) =21a(9) =26a(10) =26a(11) =35a(12) =35a(13) =46a(14) =48a(15) =57a(16) =57a(17) =70a(18) =70a(19) =85a(20) =87a(21) =100a(22) =100a(23) =117a(24) =117a(25) =136a(26) =138a(27) =155a(28) =155a(29) =176