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 A240561 #14 Apr 06 2015 21:31:08 %S A240561 0,1,-10,178,-5296,238816,-15214480,1301989648,-144118832896, %T A240561 20040052293376,-3419989086092800,702831038438522368, %U A240561 -171209091176316215296,48783404012394865985536,-16074763418934659189278720,6065554251200571899397081088,-2598468976240882751482797162496 %N A240561 The main diagonal in the difference table of A240559. %F A240561 a(n) = -Sum_{k=0..n}(C(n,k)*Euler(n+k+1)). - _Vladimir Kruchinin_, Apr 06 2015 %F A240561 a(n) ~ (-1)^(n+1) * 2^(4*n+9/2) * n^(2*n+3/2) / (exp(2*n) * Pi^(2*n+3/2)). - _Vaclav Kotesovec_, Apr 06 2015 %e A240561 a(n) is the main diagonal in this difference table D(n, k): %e A240561 [ 0, 0, 1, -3, -5, 45, 61, -1113, -1385] %e A240561 [ 0, 1, -2, -8, 40, 106, -1052, -2498] %e A240561 [ 1, -1, -10, 32, 146, -946, -3550] %e A240561 [ 0, -11, 22, 178, -800, -4496] %e A240561 [ -11, 11, 200, -622, -5296] %e A240561 [ 0, 211, -422, -5918] %e A240561 [ 211, -211, -6340] %e A240561 [ 0, -6551] %e A240561 [-6551] %e A240561 D(n, 0) = A240560(n). %e A240561 D(0, n) = A240559(n). %e A240561 D(2*n, 0) = (-1)^(n+1)*A147315(2*n, 2). %p A240561 A240561_list := proc(len) local A, m, n, k; %p A240561 n := 2*len-1; A := array(0..n, 0..n); %p A240561 for m from 0 to n do %p A240561 A[m, 0] := euler(m) + 2^(m+1)*euler(m+1,0); %p A240561 for k from m-1 by -1 to 0 do %p A240561 A[k, m-k] := A[k+1, m-k-1] - A[k, m-k-1] %p A240561 od od; [seq(A[k, k], k=0..len-1)] end: %p A240561 A240561_list(17); %t A240561 Table[-Sum[Binomial[n, k]*EulerE[n+k+1], {k, 0, n}],{n,0,20}] (* _Vaclav Kotesovec_, Apr 06 2015 *) %o A240561 (Maxima) %o A240561 a(n):=-sum(binomial(n,k)*euler(n+k+1),k,0,n); /* _Vladimir Kruchinin_, Apr 06 2015 */ %Y A240561 Cf. A147315, A240559, A240560. %K A240561 sign %O A240561 0,3 %A A240561 _Peter Luschny_, Apr 17 2014