Main Article Content
Triangular numbers have been of interest and extensively studied. In this work, we focus on an isosceles triangular number which is a generalization of a triangular number. Properties of isosceles triangular numbers have been determined together with a necessary condition for a positive integer to be isosceles triangular. Characterizations of odd and even isosceles triangular numbers have been also provided. Finally, links between isosceles triangular numbers and regular polygonal numbers has been given as well.
 J. L. Pietempol, “Square triangular numbers,” The American Mathematical Monthly, vol. 169, pp. 168-169, 1962.
 T. J. Trotter, “Some identities for the triangular numbers” Journal of Recreational Mathematics, vol. 6, pp. 128-135, 1973.
 P. J. Berana, J. Montalbo and D. Magpantay, “On triangular and trapezoidal numbers,” Asia Pacific Journal of Multidisciplinary Research, vol. 3, pp.76-81, 2015.
 H. Hindin, “Stars, hexes, triangular numbers and Pythagorean triples,” Journal of Recreational Mathematics, vol. 16, pp. 191-193, 1983-1984.
 W. L. McDaniel, “Triangular numbers in the Pell sequence,” The Fibonacci Quarterly, vol. 34, pp. 105-107, 1996.
 N. J. A. Sloane. 2017. On-line encyclopedia of integer sequences. Retrieved 2 May 2017 from https://oeis.org/