Triangle read by rows: T(n,k) (n>=2, 1<=k<=n-1) is the number of unordered pairs of vertices at distances k in the odd graph O_n.

A228308

Triangle read by rows: T(n,k) (n>=2, 1<=k<=n-1) is the number of unordered pairs of vertices at distances k in the odd graph O_n.

Terms

    a(0) =3a(1) =15a(2) =30a(3) =70a(4) =210a(5) =315a(6) =315a(7) =1260a(8) =2520a(9) =3780a(10) =1386a(11) =6930a(12) =17325a(13) =34650a(14) =46200a(15) =6006a(16) =36036a(17) =108108a(18) =270270a(19) =450450a(20) =600600a(21) =25740a(22) =180180a(23) =630630a(24) =1891890a(25) =3783780a(26) =6306300a(27) =7882875a(28) =109395a(29) =875160

External references