Primes p such that sigma(2p-1) is a prime q.

Terms

a(0) =5a(1) =13a(2) =1201a(3) =1741a(4) =2521a(5) =5101a(6) =8581a(7) =14281a(8) =41761a(9) =139921a(10) =353641a(11) =595141a(12) =697381a(13) =1460341a(14) =1639861a(15) =3723721a(16) =3889261a(17) =6093541a(18) =7956061a(19) =11143921a(20) =14199121a(21) =33874681a(22) =46938361a(23) =51521401a(24) =56063461a(25) =62395621a(26) =67523821a(27) =90706981