Numbers k such that (k*2^d + 1)*(d*2^k + 1) is semiprime for some divisor d of k.

A382887

Numbers k such that (k*2^d + 1)*(d*2^k + 1) is semiprime for some divisor d of k.

Terms

    a(0) =1a(1) =2a(2) =8a(3) =12a(4) =30a(5) =51a(6) =63a(7) =141a(8) =201a(9) =209a(10) =534a(11) =4713a(12) =5795a(13) =6611a(14) =7050a(15) =18496a(16) =24105a(17) =32292a(18) =32469a(19) =52782a(20) =59656a(21) =80190a(22) =90825

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