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 A287703 #14 Jul 28 2017 09:56:29 %S A287703 1,1,0,0,1,0,-1,0,1,0,0,-1,0,1,0,1,0,-1,0,5,0,0,1,0,-5,0,691,0,-1,0,7, %T A287703 0,-691,0,7,0,0,-2,0,691,0,-14,0,3617,0,1,0,-691,0,21,0,-25319,0, %U A287703 43867,0,0,691,0,-10,0,75957,0,-438670,0,174611,0 %N A287703 Triangle read by rows, numerators of T(n,k) = (-1)^n*binomial(n-1,k)*Bernoulli(n+k)/ (n+k) for n>=1, 0<=k<=n-1. %C A287703 For the rational triangle the reciprocals of the row sums are the Apéry numbers A005430. %F A287703 A005430(n) = 1 / (Sum_{k=0..n-1} T(n,k)) for n>=1. %e A287703 The rational triangle starts (with row sums at the end of the line): %e A287703 1: [1/2], 1/2 %e A287703 2: [1/12, 0], 1/12 %e A287703 3: [0, 1/60, 0], 1/60 %e A287703 4: [-1/120, 0, 1/84, 0], 1/280 %e A287703 5: [0, -1/63, 0, 1/60, 0], 1/1260 %e A287703 6: [1/252, 0, -1/24, 0, 5/132, 0], 1/5544 %e A287703 7: [0, 1/40, 0, -5/33, 0, 691/5460, 0], 1/24024 %e A287703 8: [-1/240, 0, 7/44, 0, -691/936, 0, 7/12, 0], 1/102960 %e A287703 9: [0, -2/33, 0, 691/585, 0, -14/3, 0, 3617/1020, 0], 1/437580 %e A287703 The numerators of the triangle are: %e A287703 1: [ 1] %e A287703 2: [ 1, 0] %e A287703 3: [ 0, 1, 0] %e A287703 4: [-1, 0, 1, 0] %e A287703 5: [ 0, -1, 0, 1, 0] %e A287703 6: [ 1, 0, -1, 0, 5, 0] %e A287703 7: [ 0, 1, 0, -5, 0, 691, 0] %e A287703 8: [-1, 0, 7, 0, -691, 0, 7, 0] %e A287703 9: [ 0, -2, 0, 691, 0, -14, 0, 3617, 0] %p A287703 T := (n,k) -> numer((-1)^n*binomial(n-1,k)*bernoulli(k+n)/(k+n)): %p A287703 for n from 1 to 9 do seq(T(n,k), k=0..n-1) od; %t A287703 T[n_, k_]:=Numerator[(-1)^n*Binomial[n - 1, k] BernoulliB[k + n]/(k + n)]; Table[T[n, k], {n, 11}, {k, 0, n - 1}]//Flatten (* _Indranil Ghosh_, Jul 27 2017 *) %o A287703 (PARI) T(n, k) = numerator((-1)^n*binomial(n-1,k)*bernfrac(k+n)/(k+n)); %o A287703 tabl(nn) = for (n=1, nn, for (k=0, n-1, print1(T(n, k), ", ")); print); \\ _Michel Marcus_, Jul 28 2017 %Y A287703 Cf. A005430 (Apéry), A287704 (denominators). %K A287703 sign,tabl,frac %O A287703 1,20 %A A287703 _Peter Luschny_, Jun 21 2017