One third of product plus sum of six consecutive nonnegative numbers.

Terms

a(0) =5a(1) =247a(2) =1689a(3) =6731a(4) =20173a(5) =50415a(6) =110897a(7) =221779a(8) =411861a(9) =720743a(10) =1201225a(11) =1921947a(12) =2970269a(13) =4455391a(14) =6511713a(15) =9302435a(16) =13023397a(17) =17907159a(18) =24227321a(19) =32303083a(20) =42504045a(21) =55255247a(22) =71042449a(23) =90417651a(24) =114004853a(25) =142506055