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A110998 Numbers n such that 23*n^2 - 9 is prime. 1
2, 4, 16, 38, 40, 44, 70, 82, 86, 88, 116, 128, 130, 142, 152, 158, 170, 178, 194, 224, 226, 238, 262, 268, 298, 304, 310, 320, 346, 352, 362, 364, 368, 392, 406, 418, 434, 446, 452, 458, 460, 472, 478, 490, 494 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..45.

EXAMPLE

If n=88 then 23*n^2 - 9 = 178103 (prime).

MATHEMATICA

Select[Range[500], PrimeQ[(23#^2 - 9)] &] (* Stefan Steinerberger, Feb 28 2006 *)

PROG

(PARI) is(n)=isprime(23*n^2-9) \\ Charles R Greathouse IV, Jun 12 2017

CROSSREFS

Sequence in context: A265835 A185074 A000216 * A051861 A296297 A290265

Adjacent sequences:  A110995 A110996 A110997 * A110999 A111000 A111001

KEYWORD

nonn,easy

AUTHOR

Parthasarathy Nambi, Sep 30 2005

EXTENSIONS

More terms from Stefan Steinerberger, Feb 28 2006

STATUS

approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)