Number of same-sized pairs of subsets of set of n numbers that might have the same sum.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =20a(6) =70a(7) =231a(8) =735a(9) =2289a(10) =7029a(11) =21384a(12) =64636a(13) =194480a(14) =583232a(15) =1744847a(16) =5210687a(17) =15540023a(18) =46299143a(19) =137837666a(20) =410127806a(21) =1219804541a(22) =3626853647a(23) =10781440394a(24) =32045015650a(25) =95236794600a(26) =283027305300a(27) =841096898745