

A002342


Least positive integer x such that p=(x^25y^2)/4 where p is the nth odd prime such that 5 is a square mod p.
(Formerly M3758 N1534)


1



5, 7, 9, 11, 12, 13, 16, 17, 17, 19, 19, 22, 21, 23, 24, 26, 27, 29, 27, 28, 29, 32, 31, 31, 33, 32, 34, 33, 37, 37, 37, 39, 41, 39, 41, 43, 41, 41, 42, 43, 44, 46, 43, 44, 47, 49, 46, 47, 47, 49, 48, 49, 53, 51, 52, 53, 56, 57, 53, 53, 54, 59, 56, 57, 58, 59, 59, 57, 58, 61
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OFFSET

1,1


COMMENTS

The nth odd prime for which 5 is a square mod p is A038872(n).


REFERENCES

A. J. C. Cunningham, Quadratic Partitions. Hodgson, London, 1904, p. 1.
D. H. Lehmer, Guide to Tables in the Theory of Numbers. Bulletin No. 105, National Research Council, Washington, DC, 1941, p. 55.
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

Table of n, a(n) for n=1..70.
A. J. C. Cunningham, Quadratic Partitions, Hodgson, London, 1904 [Annotated scans of selected pages]


EXAMPLE

5=(5^25*1^2)/4 so a(1)=5, 11=(7^25*1^2)/4 so a(2)=7.


PROG

(PARI) a(n)=local(y, p); if(n<1, 0, p=0; y=2; until(p>=n, y++; if(issquare(5+O(prime(y))), p++)); p=prime(y); y=0; until(issquare(4*p+5*y^2), y++); sqrtint(4*p+5*y^2))


CROSSREFS

Cf. A002343, A038872.
Sequence in context: A212191 A241853 A165513 * A080353 A184108 A254760
Adjacent sequences: A002339 A002340 A002341 * A002343 A002344 A002345


KEYWORD

nonn


AUTHOR

N. J. A. Sloane.


STATUS

approved



