Indices of triangular numbers (A000217) that are also centered pentagonal numbers (A005891).

A254626

Indices of triangular numbers (A000217) that are also centered pentagonal numbers (A005891).

Terms

    a(0) =1a(1) =3a(2) =23a(3) =61a(4) =421a(5) =1103a(6) =7563a(7) =19801a(8) =135721a(9) =355323a(10) =2435423a(11) =6376021a(12) =43701901a(13) =114413063a(14) =784198803a(15) =2053059121a(16) =14071876561a(17) =36840651123a(18) =252509579303a(19) =661078661101

External references