A336768 Irregular triangle where the n-th row list the positive integers which can be written in two bases smaller than n as mutually-reversed strings of digit(s), for n>=4.
1, 1, 2, 22, 1, 2, 3, 7, 22, 1, 2, 3, 4, 7, 22, 87, 9831, 1, 2, 3, 4, 5, 7, 9, 17, 22, 51, 87, 102, 2601, 9831, 314767045, 1, 2, 3, 4, 5, 6, 7, 9, 17, 22, 51, 87, 91, 102, 220, 2601, 5258, 7491, 8283, 9831, 10516, 13541, 15774, 16566, 71500, 644765, 3552340, 314767045, 1427310725, 1848187230, 1916060910
Offset: 4
Examples
Triangle begins: 4| 1; 5| 1, 2, 22; 6| 1, 2, 3, 7, 22; 7| 1, 2, 3, 4, 7, 22, 87, 9831; 8| 1, 2, 3, 4, 5, 7, 9, 17, 22, 51, 87, 102, 2601, 9831, 314767045; 9| 1, 2, 3, 4, 5, 6, 7, 9, 17, 22, 51, 87, 91, 102, 220, 2601, 5258, 7491, ... ... For n=4, there is a single integer whose base 2 and base 3 representations are each other reverse: it is 1 which is its own reverse.
Extensions
a(32) from Graham Holmes, Aug 04 2020
More terms from Jinyuan Wang, Aug 04 2020
Comments