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 A247212 #24 Aug 24 2019 10:11:51
%S A247212 1,1,0,6,12,-20,420,-252,-336,66960,-368640,2328480,2898720,
%T A247212 -117767520,1720764864,-12297479040,58230547200,312819736320,
%U A247212 -9239378296320,128087696977920,-1154590730496000,7050771080478720,398679450301440,-591762353886950400,6580219687752775680
%N A247212 Exponential generating function = (1+x)^(1+x^2).
%e A247212 (1+x)^(1+x^2) = 1+x+x^3+(1/2)*x^4-(1/6)*x^5+(7/12)*x^6-(1/20)*x^7-(1/120)*x^8+(31/168)*x^9-(32/315)*x^10+(7/120)*x^11+...
%t A247212 With[{nn=30},CoefficientList[Series[(1+x)^(1+x^2),{x,0,nn}],x] Range[ 0,nn]!] (* _Harvey P. Dale_, Aug 24 2019 *)
%o A247212 (PARI) Vec(serlaplace((1+x+O(x^25))^(1+x^2)))
%Y A247212 Cf. A005727, A007120, A247256.
%K A247212 sign
%O A247212 0,4
%A A247212 _Franklin T. Adams-Watters_, Nov 29 2014