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A257839 Smallest possible x such that 4/n = 1/x + 1/y + 1/z with 0 < x < y < z all integers, or 0 if there is no such solution. Corresponding y and z values are in A257840 and A257841. 5
0, 0, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 14, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 20, 19, 19, 20, 20, 20, 20, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

See A073101 for more details.

Otherwise said, x-value of the lexicographically first solution (x,y,z) to the given equation.

This differs from A075245 starting with a(89)=23 vs A075245(89)=24, respective solutions being 1/23 + 1/690 + 1/61410 = 1/24 + 1/306 + 1/108936 = 4/89.

LINKS

M. F. Hasler, Table of n, a(n) for n = 1..1000

PROG

(PARI) A257839(n)=for(c=n\4+1, n*3\4, for(b=c+1, ceil(2/(t=4/n-1/c))-1, numerator(t-1/b)==1&&return(c)))

CROSSREFS

Cf. A073101, A075245, A075246, A075247.

Sequence in context: A008621 A144075 A128929 * A075245 A328301 A129253

Adjacent sequences:  A257836 A257837 A257838 * A257840 A257841 A257842

KEYWORD

nonn

AUTHOR

M. F. Hasler, May 16 2015

STATUS

approved

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Last modified January 20 11:06 EST 2020. Contains 331083 sequences. (Running on oeis4.)