Indices of triangular numbers (A000217) that are also decagonal (A001107).

A133218

Indices of triangular numbers (A000217) that are also decagonal (A001107).

Terms

    a(0) =0a(1) =1a(2) =4a(3) =55a(4) =154a(5) =1885a(6) =5248a(7) =64051a(8) =178294a(9) =2175865a(10) =6056764a(11) =73915375a(12) =205751698a(13) =2510946901a(14) =6989500984a(15) =85298279275a(16) =237437281774

External references