a(n) is the least number such that there are n semiprimes pq such that (p+1)(q+1) = a(n) for each semiprime.
A180334
a(n) is the least number such that there are n semiprimes pq such that (p+1)(q+1) = a(n) for each semiprime.
Terms
- a(0) =9a(1) =24a(2) =72a(3) =144a(4) =576a(5) =1080a(6) =2160a(7) =1440a(8) =8640a(9) =20160a(10) =15120a(11) =40320a(12) =70560a(13) =60480a(14) =191520a(15) =166320a(16) =211680a(17) =514080a(18) =277200a(19) =982800a(20) =907200a(21) =1663200a(22) =831600a(23) =720720a(24) =2162160a(25) =4989600a(26) =2494800a(27) =8648640a(28) =5266800a(29) =8845200
External references
- oeis: A180334