A094408 a(n) = Sum_{k = 0..n} 3^k*A085707(n,k).
1, 1, 4, 37, 631, 17266, 692785, 38325925, 2795925136, 260056965205, 30038178784699, 4218296308789630, 707778995370264001, 139840360858571766121
Offset: 0
Crossrefs
Cf. A085707.
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.
Triangle begins: 1, 3, 5, 17, 70, 61, 155, 1143, 2317, 1385, 2073, 23716, 82286, 110556, 50521, 38227, 623753, 3243270, 7258090, 7293671, 2702765, 929569, 20454498, 147624355, 484343420, 796220487, 639139202, 199360981, ...
Triangle begins: 1; 0, 1; 0, -1, 1; 0, 3, -3, 1; 0, -17, 17, -6, 1; 0, 155, -155, 55, -10, 1; ...
h[n_, x_] := Sum[c[k]*x^k, {k, 0, n}]; eq[n_] := SolveAlways[h[n, x*(x - 1)] == EulerE[2*n, x], x]; row[n_] := Table[c[k], {k, 0, n}] /. eq[n] // First; Table[row[n], {n, 0, 10}] // Flatten (* Jean-François Alcover, Oct 02 2013 *)
{ S2(n, k) = (1/k!)*sum(i=0,k,(-1)^(k-i)*binomial(k,i)*i^n) }{ Eu(n) = sum(m=0,n,(-1)^m*m!*S2(n+1,m+1)*(-1)^floor(m/4)*2^-floor(m/2)*((m+1)%4!=0)) } T(n,k)=if(nRalf Stephan
function A006846list(len::Int) # Algorithm of L. Seidel (1877) R = Array{BigInt}(len) A = fill(BigInt(0), len+1); A[1] = 1 for n in 1:len for k in n:-1:2 A[k] += A[k+1] end for k in 2:1:n A[k] += A[k-1] end R[n] = A[n] end return R end println(A006846list(20)) # Peter Luschny, Jan 02 2018
A006846 := proc(n) option remember ; if n =0 then return 1; else add(binomial(2*n,2*m)*procname(m)/(-4)^(n-m),m=0..n-1) ; (3/4)^n-% ; end if end proc: seq(A006846(n),n=0..20) ; # R. J. Mathar, Jan 10 2018
h[n_, x_] := Sum[c[k] x^k, {k, 0, n}]; eq[n_] := SolveAlways[h[n, x*(x-1)] == EulerE[2*n, x], x]; a[n_] := Sum[(-1)^(n+k)*c[k], {k, 0, n}] /. eq[n] // First; Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Oct 02 2013, after Philippe Deléham *)
{a(n)=local(X=x+x*O(x^(2*n))); round((2*n)!*polcoeff(cosh(sqrt(3)*X/2)/cos(X/2),2*n))} \\ Paul D. Hanna
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