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 A294720 #17 Jun 18 2025 05:17:51
%S A294720 0,1,2,3,6,11,7256527
%N A294720 Palindromes in tribonacci sequence with initial values 0,1,0 (A001590).
%C A294720 7256527 is probably the last term.
%t A294720 a = c = 0; b = 1; lst = {0}; While[a < 10^7, d = a + b + c; If[ Reverse[idn = IntegerDigits[d]] == idn, AppendTo[lst, d]]; a = b; b = c; c = d]; lst (* _Robert G. Wilson v_, Nov 09 2017 *)
%Y A294720 Cf. A001590, A045504, A055391, A294688.
%K A294720 nonn,base,more,hard
%O A294720 1,3
%A A294720 _Chai Wah Wu_, Nov 07 2017