Partial sums of second pentagonal numbers with even index (A049453).

Terms

a(0) =0a(1) =7a(2) =33a(3) =90a(4) =190a(5) =345a(6) =567a(7) =868a(8) =1260a(9) =1755a(10) =2365a(11) =3102a(12) =3978a(13) =5005a(14) =6195a(15) =7560a(16) =9112a(17) =10863a(18) =12825a(19) =15010a(20) =17430a(21) =20097a(22) =23023a(23) =26220a(24) =29700a(25) =33475a(26) =37557a(27) =41958a(28) =46690a(29) =51765