Icosagonal numbers divisible by 20.

Terms

a(0) =0a(1) =20a(2) =820a(3) =1200a(4) =3440a(5) =4180a(6) =7860a(7) =8960a(8) =14080a(9) =15540a(10) =22100a(11) =23920a(12) =31920a(13) =34100a(14) =43540a(15) =46080a(16) =56960a(17) =59860a(18) =72180a(19) =75440a(20) =89200a(21) =92820a(22) =108020a(23) =112000a(24) =128640a(25) =132980a(26) =151060a(27) =155760a(28) =175280a(29) =180340