Sum_{k=2..n} min(k,n-k)*phi(k)*(n-k).

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =6a(5) =16a(6) =38a(7) =70a(8) =124a(9) =200a(10) =314a(11) =452a(12) =644a(13) =890a(14) =1216a(15) =1592a(16) =2068a(17) =2624a(18) =3312a(19) =4094a(20) =5042a(21) =6138a(22) =7438a(23) =8844a(24) =10488a(25) =12348a(26) =14496a(27) =16796a(28) =19422a(29) =22314