Concentric 14-gonal numbers.

Terms

a(0) =0a(1) =1a(2) =14a(3) =29a(4) =56a(5) =85a(6) =126a(7) =169a(8) =224a(9) =281a(10) =350a(11) =421a(12) =504a(13) =589a(14) =686a(15) =785a(16) =896a(17) =1009a(18) =1134a(19) =1261a(20) =1400a(21) =1541a(22) =1694a(23) =1849a(24) =2016a(25) =2185a(26) =2366a(27) =2549a(28) =2744a(29) =2941