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A143932 a(n) = smallest positive prime number of the form x^2 - n! (where x is a positive integer). 2
3, 2, 3, 97, 241, 241, 1201, 3361, 5569, 61441, 240769, 915049, 240769, 17302321, 7076521, 49186201, 2100735289, 1074527281, 23971813321, 32354445841, 68820869329, 2992426816129, 26238323995129, 104071698229321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For smallest positive integers x see A143931. Prime x see A143933.

LINKS

Table of n, a(n) for n=1..24.

EXAMPLE

a(1)=3 because 2^2 - 1! = 3;

a(2)=2 because 2^2 - 2! = 2;

a(3)=3 because 3^2 - 3! = 3;

a(4)=97 because 11^2 - 4! = 97.

MATHEMATICA

b = {}; Do[k = Round[Sqrt[n! ]] + 1; While[ ! PrimeQ[k^2 - n! ], k++ ]; AppendTo[b, k^2-n! ], {n, 1, 50}]; b

CROSSREFS

Cf. A121926, A143931, A143933.

Sequence in context: A139075 A089750 A109591 * A304496 A195258 A070471

Adjacent sequences:  A143929 A143930 A143931 * A143933 A143934 A143935

KEYWORD

nonn

AUTHOR

Artur Jasinski, Sep 05 2008

STATUS

approved

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Last modified January 19 22:12 EST 2022. Contains 350466 sequences. (Running on oeis4.)