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

A133217

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

Terms

    a(0) =0a(1) =1a(2) =2a(3) =20a(4) =55a(5) =667a(6) =1856a(7) =22646a(8) =63037a(9) =769285a(10) =2141390a(11) =26133032a(12) =72744211a(13) =887753791a(14) =2471161772a(15) =30157495850a(16) =83946756025

External references