Sum_{ i in 1..p-1, j in 1..p-1, i*j mod p = 1} i*j, where p = n-th prime.

Terms

a(0) =1a(1) =5a(2) =29a(3) =83a(4) =351a(5) =519a(6) =1291a(7) =1747a(8) =3357a(9) =6553a(10) =7501a(11) =11839a(12) =17219a(13) =19263a(14) =28199a(15) =38583a(16) =56049a(17) =49043a(18) =74771a(19) =96133a(20) =89059a(21) =132087a(22) =155209a(23) =185653a(24) =221741a(25) =260983a(26) =274803a(27) =331913a(28) =314355a(29) =348943