Alternating sum of 11-gonal (or hendecagonal) numbers.

Terms

a(0) =0a(1) =-1a(2) =10a(3) =-20a(4) =38a(5) =-57a(6) =84a(7) =-112a(8) =148a(9) =-185a(10) =230a(11) =-276a(12) =330a(13) =-385a(14) =448a(15) =-512a(16) =584a(17) =-657a(18) =738a(19) =-820a(20) =910a(21) =-1001a(22) =1100a(23) =-1200a(24) =1308a(25) =-1417a(26) =1534a(27) =-1652a(28) =1778a(29) =-1905