The next term should be +-1 modulo 11 and 0 modulo 5, which is impossible.
Triangular numbers cannot be so arranged.
Table of n, a(n) for n=1..9.
Sequence in context: A081482 A134475 A218030 * A013171 A073422 A006525
Adjacent sequences: A114026 A114027 A114028 * A114030 A114031 A114032
Amarnath Murthy, Nov 13 2005
Completed by Max Alekseyev, May 02 2009