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A273932 Integers n such that ceiling(sqrt(n!)) is prime. 0
2, 3, 4, 5, 7, 21, 2132, 3084, 9301 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence includes the known solutions of Brocard's problem as of 2016 (see A146968).

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

3 is in the sequence because 3! = 6, sqrt(6) = 2.449489742783178..., the ceiling of which is 3, which is prime.

4 is in the sequence because 4! = 24, sqrt(24) = 4.898979485566356..., the ceiling of which is 5, which is prime.

MATHEMATICA

Select[Range[3200]], PrimeQ[Ceiling[Sqrt[#!]]] &]

CROSSREFS

Cf. A055228 (ceiling(sqrt(n!))), A146968.

Sequence in context: A281233 A048459 A203615 * A270831 A063738 A063737

Adjacent sequences:  A273929 A273930 A273931 * A273933 A273934 A273935

KEYWORD

nonn,more

AUTHOR

Salvador Cerdá, Jun 04 2016

EXTENSIONS

a(9) from Giovanni Resta, Jun 20 2016

STATUS

approved

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Last modified July 19 03:54 EDT 2019. Contains 325144 sequences. (Running on oeis4.)