Primes q of the form sigma((p + 1) / 2) where p is a prime.

Terms

a(0) =3a(1) =7a(2) =13a(3) =31a(4) =127a(5) =307a(6) =1723a(7) =2801a(8) =3541a(9) =8191a(10) =19531a(11) =86143a(12) =131071a(13) =492103a(14) =524287a(15) =552793a(16) =684757a(17) =704761a(18) =735307a(19) =797161a(20) =1353733a(21) =1886503a(22) =3413257a(23) =3894703a(24) =5473261a(25) =7094233a(26) =7781311a(27) =9250723a(28) =10378063a(29) =12655807