Prime numbers n such that 2^n-1 is prime and can be written in the form a^2+7*b^2.

A216518

Prime numbers n such that 2^n-1 is prime and can be written in the form a^2+7*b^2.

Terms

    a(0) =3a(1) =7a(2) =13a(3) =19a(4) =31a(5) =61a(6) =127a(7) =607a(8) =1279a(9) =2203a(10) =2281a(11) =3217a(12) =4423a(13) =23209a(14) =44497a(15) =110503a(16) =132049a(17) =216091a(18) =1257787a(19) =13466917a(20) =20996011a(21) =24036583a(22) =30402457a(23) =42643801

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