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 A246958 #20 Jun 16 2025 15:29:44
%S A246958 2,6,152,811008,15502126646034432,
%T A246958 8348302506064411039310051552485442040121786368
%N A246958 Number of directed Hamiltonian paths in the n-Sierpiński gasket graph that starts at the fixed corner.
%C A246958 Explicit formula and asymptotic are given by Chang and Chen (2011).
%C A246958 a(7) contains 134 decimal digits.
%H A246958 S.-C. Chang, L.-C. Chen. Hamiltonian walks on the Sierpinski gasket, J. Math. Phys. 52 (2011), 023301. doi:<a href="http://dx.doi.org/10.1063/1.3545358">10.1063/1.3545358</a>. See <a href="http://arxiv.org/abs/0909.5541">also</a>, arXiv:0909.5541 [cond-mat.stat-mech], 2009.
%H A246958 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianPath.html">Hamiltonian Path</a>.
%H A246958 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SierpinskiGasketGraph.html">Sierpiński Gasket Graph</a>.
%t A246958 a[n_] := Module[{m}, If[n == 1, Return[2]]; m = 3^(n-2); 2^m*3^((m-1)/2)* (7*17/(2^4*3^3)*4^(n-1) + 2^2*13/3^3 - If[n == 2, 1/(2^2*3^2), 0])];
%t A246958 Array[a, 6] (* _Jean-François Alcover_, Dec 04 2018, from PARI *)
%o A246958 (PARI) A246958(n) = if(n==1,return(2)); my(m=3^(n-2)); 2^m * 3^((m-1)/2) * ( 7*17/(2^4*3^3)*4^(n-1) + 2^2*13/(3^3) - if(n==2,1/(2^2*3^2) ) )
%Y A246958 Cf. A234635, A246957, A246959.
%K A246958 nonn
%O A246958 1,1
%A A246958 _Max Alekseyev_, Sep 08 2014