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 A276051 #11 Dec 07 2018 04:56:40 %S A276051 1,2,4,10,28,80,244,732,2320,7172,23212,73228,240184,768932,2545568, %T A276051 8240604,27468352,89699652,300579836,988463844 %N A276051 a(n) is the number of top arches with length =1 for all semi meander solutions with n top arches. %F A276051 Conjectured formula for n>=3. %F A276051 M(n)= number of semi meanders solutions for n top arches. A000682. %F A276051 r(x)= number of top arches with no covering arch for solution x of M(n). %F A276051 Example: /\ r(x)=3 %F A276051 /\/\//\\ %F A276051 h(x)= number of top arches with length =1 for solution x of M(n). %F A276051 Example: /\ %F A276051 /\/\//\\ h(x)=3 %F A276051 i(x)= number of uncovered top arches with length =1 and in an internal position for solution x of M(n). Example:() /\ i(x)=1 %F A276051 /\(/\)//\\ %F A276051 a(n+1)= sum of x=1 to M(n)for [r(x)*h(x)-i(x)] + 2*M(n)-2*M(n-1) %F A276051 a(5)=(3*3-1)+(3*3-1)+(2*2-0)+(2*2-0)+2*4-2*2= 28. %e A276051 a(4)=10 /\ /\ /\ /\ %e A276051 /\/\//\\ //\\ //\\/\/\ //\\ %e A276051 /\///\\\ ///\\\/\. %Y A276051 Cf. A000682. %K A276051 nonn,more %O A276051 1,2 %A A276051 _Roger Ford_, Aug 17 2016 %E A276051 a(11)-a(20) from _Andrew Howroyd_, Dec 07 2018