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A216071 Brocard's problem: positive integers m such that m^2 = n! + 1 for some n. 4
5, 11, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A085692 and A146968 for links, references and comments. - M. F. Hasler, Nov 20 2018

LINKS

Table of n, a(n) for n=1..3.

FORMULA

a(n) = A000196(A085692(n)) = A000196(A038507(A146968(n))) where A000196 = sqrt and A038507(n) = n! + 1. - M. F. Hasler, Nov 20 2018

MATHEMATICA

Sqrt[#!+1]&/@Select[Range[1000], IntegerQ[Sqrt[#!+1]]&] (* Harvey P. Dale, Sep 29 2012 *)

PROG

(PARI) apply( sqrtint, A085692) \\ M. F. Hasler, Nov 20 2018

(PARI) select( is_A216071(m)=m^2==A084558(m^2)!+1, [0..99]) \\ M. F. Hasler, Nov 20 2018

CROSSREFS

A085692, A146968, A216071 are all essentially the same sequence. - N. J. A. Sloane, Sep 01 2012

Sequence in context: A121170 A239322 A101209 * A050568 A065555 A189802

Adjacent sequences:  A216068 A216069 A216070 * A216072 A216073 A216074

KEYWORD

nonn,hard,bref

AUTHOR

V. Raman, Sep 01 2012

STATUS

approved

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Last modified October 17 04:09 EDT 2019. Contains 328106 sequences. (Running on oeis4.)