a(n) = x is the smallest number such that gcd(prime(x)-1,x-1) = n.

Terms

a(0) =1a(1) =3a(2) =4a(3) =13a(4) =36a(5) =19a(6) =120a(7) =33a(8) =46a(9) =11a(10) =78a(11) =37a(12) =560a(13) =239a(14) =496a(15) =1905a(16) =52a(17) =397a(18) =3250a(19) =221a(20) =778a(21) =573a(22) =2738a(23) =25a(24) =26a(25) =287a(26) =352a(27) =477a(28) =552a(29) =271