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A074268 Primes of the form p^2 - p + 1 where p is prime. 9
3, 7, 43, 157, 4423, 6163, 19183, 22651, 26407, 37057, 113233, 121453, 143263, 208393, 292141, 375157, 412807, 527803, 590593, 843643, 981091, 1041421, 1193557, 1246573, 1441201, 1514131, 1905781, 2023507, 2397853, 2453923, 2548813, 2626021, 2864557 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Note that p^2 - p + 1 = p * phi(p) + 1 when p is prime.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Table[p = Prime[n]; p*EulerPhi[p] + 1, {n, 270}], PrimeQ] (* Arkadiusz Wesolowski, Dec 13 2011 *)

Select[Table[p^2-p+1, {p, Prime[Range[300]]}], PrimeQ] (* Harvey P. Dale, Sep 22 2015 *)

CROSSREFS

Cf. A065508 (values of p).

Sequence in context: A107636 A303160 A258435 * A019026 A181729 A162455

Adjacent sequences:  A074265 A074266 A074267 * A074269 A074270 A074271

KEYWORD

nonn,easy

AUTHOR

Enoch Haga, Jan 16 2004

STATUS

approved

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Last modified July 30 19:15 EDT 2021. Contains 346359 sequences. (Running on oeis4.)