Numbers k such that the k-th centered pentagonal number A005891(k) = (5k^2 + 5k + 2)/2 is a square.
A129556
Numbers k such that the k-th centered pentagonal number A005891(k) = (5k^2 + 5k + 2)/2 is a square.
Terms
- a(0) =0a(1) =2a(2) =21a(3) =95a(4) =816a(5) =3626a(6) =31005a(7) =137711a(8) =1177392a(9) =5229410a(10) =44709909a(11) =198579887a(12) =1697799168a(13) =7540806314a(14) =64471658493a(15) =286352060063
External references
- oeis: A129556