1,1

See A236681 for motivation.

Table of n, a(n) for n=1..17.

The solutions are {[9, 9, 9], [12, 8, 8], [15, 10, 6], [18, 9, 6], [20, 12, 5], [21, 7, 7], [24, 8, 6], [28, 21, 4], [30, 10, 5], [36, 18, 4], [42, 7, 6], [45, 9, 5], [48, 16, 4], [60, 15, 4], [84, 14, 4], [120, 8, 5], [156, 13, 4]}.

(PARI) S=1/3; for(a=1+1\S, 999, for(b=ceil(2/(S-1/a)), a, numerator(S-1/a-1/b)==1 && print1(a", ")+next(2)))

Sequence in context: A248903 A138945 A119486 * A161345 A102655 A308748

Adjacent sequences: A235338 A235339 A235340 * A235342 A235343 A235344

nonn,fini,full

M. F. Hasler, Jan 30 2014

approved