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A007663 Fermat quotients: (2^(p-1)-1)/p, where p=prime(n).
(Formerly M2828)
+0
7
1, 3, 9, 93, 315, 3855, 13797, 182361, 9256395, 34636833, 1857283155, 26817356775, 102280151421, 1497207322929, 84973577874915, 4885260612740877, 18900352534538475, 1101298153654301589, 16628050996019877513 (list; graph; listen)
OFFSET

2,2

COMMENT

The only terms that are perfect squares are a(2) = 1 and a(4) = 9. - Nick Hobson (nickh(AT)qbyte.org), May 20 2007

REFERENCES

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

L. E. Dickson, History of the Theory of Numbers. Carnegie Institute Public. 256, Washington, DC, Vol. 1, 1919; Vol. 2, 1920; Vol. 3, 1923, see vol. 1, p. 105.

D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, 70.

LINKS

T. D. Noe, Table of n, a(n) for n=2..100

H. S. Vandiver, Fermat's Quotients And Related Arithmetic Functions

H. S. Vandiver, New Types Of Congruences Involving Bernoulli Numbers and Fermat's Quotient

H. S. Vandiver, On Congruences Which Relate The Fermat And Wilson Quotients To The Bernoulli Numbers

Nick Hobson, Fermat squares.

FORMULA

a(n) = 3*A096060(n) for n>2. a(n) = 3*A001045(prime(n)-1)/prime(n) for n>1. - Alexander Adamchuk (alex(AT)kolmogorov.com), Oct 01 2006

CROSSREFS

Cf. A002322, A001917, A096060, A001045.

Sequence in context: A067210 A018654 A003225 this_sequence A018695 A156336 A078221

Adjacent sequences: A007660 A007661 A007662 this_sequence A007664 A007665 A007666

KEYWORD

nonn,easy,nice

AUTHOR

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

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Last modified November 22 15:28 EST 2009. Contains 167310 sequences.


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