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A030064 1 + product of any two terms is a square. 0
0, 2, 4, 12, 420 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

Martin Gardner, probably "Mathematical Magic Show".

LINKS

Table of n, a(n) for n=1..5.

A. Baker and H. Davenport, The Equations 3x^2-2=y^2 and 8x^2-7=z^2, Quart. J. Math. Oxford 20 (1969).

EXAMPLE

0*2,4,12,420 + 1 = 1

2*4 + 1 = 9

2*12 + 1 = 25

2*420 + 1 = 841 -> sqrt = 29

4*12 + 1 = 49

4*420 + 1 = 1681 -> sqrt = 41

12*420 + 1 = 5041 -> sqrt = 71

CROSSREFS

Sequence in context: A291827 A287059 A059085 * A224886 A180500 A176990

Adjacent sequences: A030061 A030062 A030063 * A030065 A030066 A030067

KEYWORD

nonn,fini,full

AUTHOR

Timothy Chow (tchow(AT)math.lsa.umich.edu)

EXTENSIONS

Corrected by Mitch Harris, Apr 24 2006

STATUS

approved

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Last modified January 28 08:35 EST 2023. Contains 359850 sequences. (Running on oeis4.)