Numbers k such that the sum of the k-th triangular number and (k+2)-nd triangular number is a triangular number.

A076049

Numbers k such that the sum of the k-th triangular number and (k+2)-nd triangular number is a triangular number.

Terms

    a(0) =0a(1) =3a(2) =8a(3) =25a(4) =54a(5) =153a(6) =322a(7) =899a(8) =1884a(9) =5247a(10) =10988a(11) =30589a(12) =64050a(13) =178293a(14) =373318a(15) =1039175a(16) =2175864a(17) =6056763a(18) =12681872a(19) =35301409a(20) =73915374a(21) =205751697a(22) =430810378a(23) =1199208779a(24) =2510946900a(25) =6989500983a(26) =14634871028a(27) =40737797125

External references