phi(n) + phi(reverse(n)) = sigma(n).

Terms

a(0) =3a(1) =26a(2) =221a(3) =635a(4) =1702a(5) =4945a(6) =5038a(7) =26596a(8) =27927a(9) =62783a(10) =195723a(11) =210221a(12) =364287a(13) =489955a(14) =495995a(15) =525833a(16) =901303a(17) =909503a(18) =2747761a(19) =2750247a(20) =2941119a(21) =3926146a(22) =4463651a(23) =4484831a(24) =4630475a(25) =4769947a(26) =5531305a(27) =6099313a(28) =6482845a(29) =6917881