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 A371429 #11 Mar 23 2024 10:56:41
%S A371429 1,3,12,55,272,1413,7599,41933,236053,1350093,7822620,45817390,
%T A371429 270815730,1613300978,9676131942,58380176644,354081959367,
%U A371429 2157570900137,13201923181308,81084900544971,499711105642851,3089163236655363,19150916212748940,119031956868317285
%N A371429 Expansion of (1/x) * Series_Reversion( x / ((1+x)^3 - x^4) ).
%H A371429 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A371429 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} (-1)^k * binomial(n+1,k) * binomial(3*n-3*k+3,n-4*k).
%o A371429 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^3-x^4))/x)
%o A371429 (PARI) a(n) = sum(k=0, n\4, (-1)^k*binomial(n+1, k)*binomial(3*n-3*k+3, n-4*k))/(n+1);
%Y A371429 Cf. A107264, A127897, A371428.
%Y A371429 Cf. A369159.
%K A371429 nonn
%O A371429 0,2
%A A371429 _Seiichi Manyama_, Mar 23 2024