Indices of centered square numbers (A001844) which are also pentagonal numbers (A000326).

A254710

Indices of centered square numbers (A001844) which are also pentagonal numbers (A000326).

Terms

    a(0) =1a(1) =2a(2) =9a(3) =22a(4) =119a(5) =300a(6) =1651a(7) =4172a(8) =22989a(9) =58102a(10) =320189a(11) =809250a(12) =4459651a(13) =11271392a(14) =62114919a(15) =156990232a(16) =865149209a(17) =2186591850a(18) =12049974001a(19) =30455295662a(20) =167834486799a(21) =424187547412

External references