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 A075803 #9 Mar 10 2025 05:08:42 %S A075803 1,1,2,1,1,4,11,11,22,11,11,24,10,20,10,10,10,20,10,11,20,40,20,21,10, %T A075803 10,30,20,10,10,41,20,20,20,11,10,20,10,10,10,30,11,20,20,61,10,10,10, %U A075803 20,10,10,10,10,21,20,20,20,20,21,10,10,10,10,10,10,10,12,110,110,220 %N A075803 Differences between adjacent palindromic squarefree numbers. %e A075803 a(1)=2-1=1, a(3)=5-3=2, a(6)=11-7=4. %p A075803 test := proc(n) local d; d := convert(n,base,10); return ListTools[Reverse](d)=d and numtheory[mobius](n)<>0; end; s := []; for n from 1 to 1500 do if test(n) then s := [op(s),n]; end; od; a := [op(2..-1,s)-op(1..-2,s)]; %Y A075803 Cf. A037010. %Y A075803 First differences of A071251. %K A075803 nonn,base %O A075803 1,3 %A A075803 _Jani Melik_, Oct 13 2002 %E A075803 Edited by _Dean Hickerson_, Oct 21 2002