A137761 Distinct numbers in writing first denominator and then numerator (left to right) of Leibniz's harmonic-like triangle.
1, 2, 3, 6, 5, 4, 12, 7, 20, 9, 30, 31, 11, 60, 49, 42, 13, 105, 71, 140, 209, 8, 56, 15, 168, 97, 280, 351, 72, 17, 252, 127, 504, 545, 630, 1471, 10, 90, 19, 360, 161, 840, 799, 1260, 2561, 110, 21, 495, 199, 1320, 1121, 2310, 4159, 2772, 10625
Offset: 1
Examples
1/1; --> 1 1/2, 1/2; --> 2 1/3, 5/6, 1/3; --> 3 6 5 1/4, 7/12, 7/12, 1/4; 1/5, 9/20, 31/30, 9/20, 1/5;