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A239233 Smaller member in a set of two distinct odd numbers the sum of whose reciprocals is 2/(2*n - 1), or 0 if no such integer exists. 1
0, 0, 3, 0, 5, 0, 7, 9, 9, 0, 11, 0, 13, 15, 15, 0, 17, 21, 19, 21, 21, 0, 23, 0, 25, 27, 27, 33, 29, 0, 31, 33, 33, 0, 35, 0, 37, 39, 39, 0, 41, 0, 43, 45, 45, 49, 47, 57, 49, 51, 51, 0, 53, 0, 55, 57, 57, 69, 59, 63, 61, 63, 63, 0, 65, 0, 67, 69, 69, 0, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n) = 0 if and only if n = 1 or 2*n - 1 is in A002145.

LINKS

Table of n, a(n) for n=1..71.

EXAMPLE

a(5) = 5 because 2/9 = 1/5 + 1/45.

PROG

(PARI) print1(0, ", "); forstep(n=3, 141, 2, f=2/n; y=0; if(!(isprime(n)&&Mod(n, 4)==3), y=2*floor((n+1)/4)+1; until(y==n, if(numerator(f-1/y)==1, break); y=y+2)); print1(y, ", "));

CROSSREFS

Cf. A239036.

Sequence in context: A281648 A325962 A210451 * A051704 A049689 A227901

Adjacent sequences:  A239230 A239231 A239232 * A239234 A239235 A239236

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Mar 13 2014

STATUS

approved

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Last modified July 14 16:21 EDT 2020. Contains 335729 sequences. (Running on oeis4.)