Numbers k such that k^(k + 1) == k + 1 (mod 2*k + 1) while 2*k+1 is not prime.

Terms

a(0) =1023a(1) =1638a(2) =14670a(3) =21399a(4) =24570a(5) =40290a(6) =44178a(7) =45375a(8) =52326a(9) =98046a(10) =128499a(11) =135975a(12) =157410a(13) =229494a(14) =244998a(15) =257223a(16) =370875a(17) =400302a(18) =419430a(19) =436590a(20) =458163a(21) =502326a(22) =625974a(23) =686826a(24) =754854a(25) =839270a(26) =905786a(27) =993510a(28) =1102983a(29) =1134546