5 times heptagonal numbers: a(n) = 5*n*(5*n-3)/2.

Terms

a(0) =0a(1) =5a(2) =35a(3) =90a(4) =170a(5) =275a(6) =405a(7) =560a(8) =740a(9) =945a(10) =1175a(11) =1430a(12) =1710a(13) =2015a(14) =2345a(15) =2700a(16) =3080a(17) =3485a(18) =3915a(19) =4370a(20) =4850a(21) =5355a(22) =5885a(23) =6440a(24) =7020a(25) =7625a(26) =8255a(27) =8910a(28) =9590a(29) =10295