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 A193739 #25 Aug 17 2021 02:47:32 %S A193739 1,1,1,2,2,1,3,3,2,1,4,4,3,2,1,5,5,4,3,2,1,6,6,5,4,3,2,1,7,7,6,5,4,3, %T A193739 2,1,8,8,7,6,5,4,3,2,1,9,9,8,7,6,5,4,3,2,1,10,10,9,8,7,6,5,4,3,2,1,11, %U A193739 11,10,9,8,7,6,5,4,3,2,1,12,12,11,10,9,8,7,6,5,4,3,2,1,13,13,12 %N A193739 Mirror of the triangle A193738. %C A193739 This sequence is obtained by reversing the rows of the triangle A193738. %C A193739 Except for the first term, this sequence gives the integers occurring in the song "One man went to mow". %H A193739 Reinhard Zumkeller, <a href="/A193739/b193739.txt">Rows n = 0..100 of triangle, flattened</a> %H A193739 BBC, <a href="https://www.bbc.co.uk/teach/school-radio/nursery-rhymes-one-man-went-to-mow/zjgnmfr">One man went to mow.</a> %H A193739 <a href="/index/So#songs">Index entries for sequences related to songs</a> %F A193739 Write w(n,k) for the triangle at A193738. The current triangle is then given by w(n,n-k). %e A193739 First six rows: %e A193739 1 %e A193739 1....1 %e A193739 2....2....1 %e A193739 3....3....2....1 %e A193739 4....4....3....2...1 %e A193739 5....5....4....3...2...1 %t A193739 z = 12; %t A193739 p[0, x_] := 1 %t A193739 p[n_, x_] := x*p[n - 1, x] + 1; p[n_, 0] := p[n, x] /. x -> 0 %t A193739 q[n_, x_] := p[n, x] %t A193739 t[n_, k_] := Coefficient[p[n, x], x^(n - k)]; %t A193739 t[n_, n_] := p[n, x] /. x -> 0; %t A193739 w[n_, x_] := Sum[t[n, k]*q[n + 1 - k, x], {k, 0, n}]; w[-1, x_] := 1 %t A193739 g[n_] := CoefficientList[w[n, x], {x}] %t A193739 TableForm[Table[Reverse[g[n]], {n, -1, z}]] %t A193739 Flatten[Table[Reverse[g[n]], {n, -1, z}]] (* A193738 *) %t A193739 TableForm[Table[g[n], {n, -1, z}]] %t A193739 Flatten[Table[g[n], {n, -1, z}]] (* A193739 *) %o A193739 (Haskell) %o A193739 a193738 n k = a193738_tabl !! n !! k %o A193739 a193738_row n = a193738_tabl !! n %o A193739 a193738_tabl = map reverse a193739_tabl %o A193739 -- _Reinhard Zumkeller_, May 11 2013 %Y A193739 Cf. A193738. %K A193739 nonn,tabl %O A193739 0,4 %A A193739 _Clark Kimberling_, Aug 04 2011