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 A294653 #21 Nov 10 2017 05:55:10 %S A294653 1,1,-1,1,-1,-1,1,-1,-4,0,1,-1,-16,-23,0,1,-1,-64,-713,-229,1,1,-1, %T A294653 -256,-19619,-64807,-2761,0,1,-1,-1024,-531185,-16757533,-9688425, %U A294653 -42615,1,1,-1,-4096,-14347883,-4294435855,-30499541197,-2165979799,-758499,0 %N A294653 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1-j^(k*j)*x^j) in powers of x. %H A294653 Seiichi Manyama, <a href="/A294653/b294653.txt">Antidiagonals n = 0..52, flattened</a> %F A294653 A(0,k) = 1 and A(n,k) = -(1/n) * Sum_{j=1..n} (Sum_{d|j} d^(1+k*j)) * A(n-j,k) for n > 0. %e A294653 Square array begins: %e A294653 1, 1, 1, 1, 1, ... %e A294653 -1, -1, -1, -1, -1, ... %e A294653 -1, -4, -16, -64, -256, ... %e A294653 0, -23, -713, -19619, -531185, ... %e A294653 0, -229, -64807, -16757533, -4294435855, ... %t A294653 rows = 10; %t A294653 col[k_] := col[k] = CoefficientList[Product[(1 - j^(k*j)*x^j), {j, 1, rows + 3}] + O[x]^(rows + 3), x]; %t A294653 A[n_, k_] := col[k][[n + 1]]; %t A294653 (* or: *) %t A294653 A[0, _] = 1; A[n_, k_] := A[n, k] = -(1/n)*Sum[DivisorSum[j, #^(1 + k*j) &]*A[n - j, k], {j, 1, n}]; %t A294653 Table[A[n - k, k], {n, 0, rows - 1}, {k, n, 0, -1}] // Flatten (* _Jean-François Alcover_, Nov 10 2017 *) %Y A294653 Columns k=0..1 give A010815, A292312. %Y A294653 Rows n=0..2 give A000012, (-1)*A000012, (-1)*A000302. %Y A294653 Cf. A283675, A294758. %K A294653 sign,tabl %O A294653 0,9 %A A294653 _Seiichi Manyama_, Nov 06 2017