Partial sums of Wagstaff numbers A000978.

Terms

a(0) =3a(1) =8a(2) =15a(3) =26a(4) =39a(5) =56a(6) =75a(7) =98a(8) =129a(9) =172a(10) =233a(11) =312a(12) =413a(13) =540a(14) =707a(15) =898a(16) =1097a(17) =1410a(18) =1757a(19) =2458a(20) =4167a(21) =6784a(22) =10323a(23) =16130a(24) =26631a(25) =37322a(26) =48601a(27) =60992a(28) =75471a(29) =118208