a(n) is the least k such that k^2 + 1 is a semiprime p*q, p < q, and (q - p)/2^n is prime.
A258780
a(n) is the least k such that k^2 + 1 is a semiprime p*q, p < q, and (q - p)/2^n is prime.
Terms
- a(0) =8a(1) =12a(2) =140a(3) =64a(4) =2236a(5) =196a(6) =1300a(7) =1600a(8) =6256a(9) =5084a(10) =248756a(11) =246196a(12) =484400a(13) =36680a(14) =887884a(15) =821836a(16) =1559116a(17) =104120a(18) =126072244a(19) =9586736a(20) =4156840a(21) =542759984a(22) =1017981724a(23) =2744780140a(24) =405793096a(25) =148647496a(26) =1671024916
External references
- oeis: A258780