This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A273932 #32 Jun 16 2025 00:32:28 %S A273932 2,3,4,5,7,21,2132,3084,9301 %N A273932 Integers m such that ceiling(sqrt(m!)) is prime. %C A273932 This sequence includes the known solutions of Brocard's problem as of 2016 (see A146968). %e A273932 3 is a term because 3! = 6, sqrt(6) = 2.449489742783178..., the ceiling of which is 3, which is prime. %e A273932 4 is a term because 4! = 24, sqrt(24) = 4.898979485566356..., the ceiling of which is 5, which is prime. %t A273932 Select[Range[3200], PrimeQ[Ceiling[Sqrt[#!]]] &] %o A273932 (Python) %o A273932 from math import isqrt, factorial %o A273932 from itertools import count, islice %o A273932 from sympy import isprime %o A273932 def A273932_gen(): # generator of terms %o A273932 return filter(lambda n:isprime(1+isqrt(factorial(n)-1)),count(1)) %o A273932 A273932_list = list(islice(A273932_gen(),7)) # _Chai Wah Wu_, Jul 29 2022 %Y A273932 Cf. A055228 (ceiling(sqrt(n!))), A146968. %K A273932 nonn,more,hard %O A273932 1,1 %A A273932 _Salvador Cerdá_, Jun 04 2016 %E A273932 a(9) from _Giovanni Resta_, Jun 20 2016