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 A264430 #19 Mar 28 2020 05:27:29 %S A264430 1,0,1,0,1,1,0,2,3,1,0,6,11,6,1,0,23,50,35,10,1,0,106,268,225,85,15,1, %T A264430 0,568,1645,1603,735,175,21,1,0,3459,11348,12572,6713,1960,322,28,1,0, %U A264430 23544,86775,107738,65352,22323,4536,546,36,1,0,176850,727629,1001895,678980,263865,63021,9450,870,45,1 %N A264430 Triangle read by rows, Bell transform of second order Bell numbers (A187761). %H A264430 Peter Luschny, <a href="https://oeis.org/wiki/User:Peter_Luschny/BellTransform">The Bell transform</a> %e A264430 Triangle starts: %e A264430 [1] %e A264430 [0, 1] %e A264430 [0, 1, 1] %e A264430 [0, 2, 3, 1] %e A264430 [0, 6, 11, 6, 1] %e A264430 [0, 23, 50, 35, 10, 1] %e A264430 [0, 106, 268, 225, 85, 15, 1] %e A264430 [0, 568, 1645, 1603, 735, 175, 21, 1] %e A264430 [0, 3459, 11348, 12572, 6713, 1960, 322, 28, 1] %t A264430 nmax = 10; %t A264430 A187761[n_] := Sum[BellY[n, k, BellB /@ Range[0, n-1]], {k, 0, n}]; %t A264430 Table[BellY[n, k, A187761 /@ Range[0, nmax]], {n, 0, nmax}, {k, 0, n}] // Flatten (* _Jean-François Alcover_, Jul 10 2019 *) %o A264430 (Sage) # uses[bell_transform from A264428] %o A264430 def A264430_triangle(dim): %o A264430 uno = [1]*dim %o A264430 bell_numbers = [sum(bell_transform(n, uno)) for n in range(dim)] %o A264430 bell_number_2 = [sum(bell_transform(n, bell_numbers)) for n in range(dim)] %o A264430 for n in range(dim): print(bell_transform(n, bell_number_2)) %o A264430 A264430_triangle(10) %Y A264430 Cf. A000110, A187761, A264428. %K A264430 nonn,tabl %O A264430 0,8 %A A264430 _Peter Luschny_, Nov 13 2015