Triangular numbers k*(k+1)/2 such that A068865(k) = k*(k+1)/2.

Terms

a(0) =1a(1) =3a(2) =6a(3) =10a(4) =28a(5) =36a(6) =45a(7) =78a(8) =91a(9) =105a(10) =136a(11) =406a(12) =465a(13) =561a(14) =666a(15) =703a(16) =946a(17) =1081a(18) =3240a(19) =6555a(20) =7260a(21) =9045a(22) =32640a(23) =46971a(24) =47586a(25) =48828a(26) =51360a(27) =70876a(28) =72390a(29) =94395