Concentric 23-gonal numbers.

Terms

a(0) =0a(1) =1a(2) =23a(3) =47a(4) =92a(5) =139a(6) =207a(7) =277a(8) =368a(9) =461a(10) =575a(11) =691a(12) =828a(13) =967a(14) =1127a(15) =1289a(16) =1472a(17) =1657a(18) =1863a(19) =2071a(20) =2300a(21) =2531a(22) =2783a(23) =3037a(24) =3312a(25) =3589a(26) =3887a(27) =4187a(28) =4508a(29) =4831