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A001912 Numbers n such that 4*n^2 + 1 is prime.
(Formerly M0636 N0232)
+0
14
1, 2, 3, 5, 7, 8, 10, 12, 13, 18, 20, 27, 28, 33, 37, 42, 45, 47, 55, 58, 60, 62, 63, 65, 67, 73, 75, 78, 80, 85, 88, 90, 92, 102, 103, 105, 112, 115, 118, 120, 125, 128, 130, 132, 135, 140, 142, 150, 153, 157, 163, 170, 175, 192, 193, 198, 200 (list; graph; listen)
OFFSET

1,2

REFERENCES

E. Kogbetliantz and A. Krikorian, Handbook of First Complex Prime Numbers, Gordon and Breach, NY, 1971, p. 1.

M. Kraitchik, Recherches sur la Th\'{e}orie des Nombres. Gauthiers-Villars, Paris, Vol. 1, 1924, Vol. 2, 1929, see Vol. 1, p. 11.

C. S. Ogilvy, Tomorrow's Math. 2nd ed., Oxford Univ. Press, 1972, p. 116.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

Marek Wolf, Search for primes of the form m^2+1

FORMULA

a(n) = A005574(n+1)/2.

MATHEMATICA

lst={}; Do[If[PrimeQ[4*n^2+1], AppendTo[lst, n]], {n, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Sep 04 2008]

CROSSREFS

Cf. A002496, A005574, A062325, A090693.

Sequence in context: A047222 A028763 A143826 this_sequence A083027 A060107 A159556

Adjacent sequences: A001909 A001910 A001911 this_sequence A001913 A001914 A001915

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified December 2 11:54 EST 2009. Contains 167921 sequences.


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