This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A336768 #30 Jun 29 2025 18:30:18 %S A336768 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, %T A336768 102,2601,9831,314767045,1,2,3,4,5,6,7,9,17,22,51,87,91,102,220,2601, %U A336768 5258,7491,8283,9831,10516,13541,15774,16566,71500,644765,3552340,314767045,1427310725,1848187230,1916060910 %N 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. %C A336768 If k is in row n then k is in row n+1. - _David A. Corneth_, Aug 04 2020 %e A336768 Triangle begins: %e A336768 4| 1; %e A336768 5| 1, 2, 22; %e A336768 6| 1, 2, 3, 7, 22; %e A336768 7| 1, 2, 3, 4, 7, 22, 87, 9831; %e A336768 8| 1, 2, 3, 4, 5, 7, 9, 17, 22, 51, 87, 102, 2601, 9831, 314767045; %e A336768 9| 1, 2, 3, 4, 5, 6, 7, 9, 17, 22, 51, 87, 91, 102, 220, 2601, 5258, 7491, ... %e A336768 ... %e A336768 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. %Y A336768 Cf. A336733 (row index 10), A336827 (right diagonal). %K A336768 nonn,base,tabf %O A336768 4,3 %A A336768 _Michel Marcus_, Aug 04 2020 %E A336768 a(32) from _Graham Holmes_, Aug 04 2020 %E A336768 More terms from _Jinyuan Wang_, Aug 04 2020