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 A367591 #18 Nov 24 2023 21:16:29 %S A367591 1,10,64,334,1549,6652,27064,105796,401041,1483606,5380840,19198306, %T A367591 67559437,234963352,808919632,2760370984,9346519297,31429487170, %U A367591 105039380080,349114288150,1154561484781,3801030845140,12462203297224,40705156945324,132494756301649 %N A367591 Expansion of 1/((1-x) * (1-3*x)^3). %H A367591 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (10,-36,54,-27). %F A367591 a(n) = ((2*n^2+4*n+3) * 3^(n+1) - 1)/8. %o A367591 (PARI) a(n) = ((2*n^2+4*n+3)*3^(n+1)-1)/8; %Y A367591 Partial sums of A027472. %Y A367591 Cf. A055580, A367592. %K A367591 nonn,easy %O A367591 0,2 %A A367591 _Seiichi Manyama_, Nov 24 2023