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A236681
Positive integers a such that there exist integers b, c > 0 with 1/a + 1/b + 1/c = 1/2.
6
3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, 24, 42
OFFSET
1,1
COMMENTS
According to J. Baez, the reason why 42 is the Answer to the Ultimate Question of Life, the Universe, and Everything, cf. LINK.
A subsequence of A236681.
EXAMPLE
The solutions [a,b,c] such that 1/a + 1/b + 1/c = 1/2 are {[3, 12, 12], [3, 7, 42], [3, 8, 24], [3, 9, 18], [3, 10, 15], [4, 5, 20], [4, 6, 12] [4, 8, 8], [5, 5, 10], [6, 6, 6]}.
PROG
(PARI) S=[]; for(a=2, 99, for(b=2, a, numerator(1/2-1/a-1/b)==1 && (S=setunion(S, Set([a, b, 1/(1/2-1/a-1/b)]))) && next(2))); S
CROSSREFS
Sequence in context: A114036 A261793 A262288 * A160238 A039165 A138220
KEYWORD
nonn,fini,full
AUTHOR
M. F. Hasler, Jan 29 2014
STATUS
approved