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 A011967 #23 Feb 13 2025 01:30:13 %S A011967 4,15,67,322,1657,9089,52922,325869,2114719,14418716,103004851, %T A011967 769052061,5987339748,48506099635,408157244967,3561086589202, %U A011967 32164670915029,300324194090773,2894932531218482,28773297907499129 %N A011967 4th differences of Bell numbers. %H A011967 Chai Wah Wu, <a href="/A011967/b011967.txt">Table of n, a(n) for n = 0..250</a> %H A011967 Cohn, Martin; Even, Shimon; Menger, Karl, Jr.; Hooper, Philip K.; <a href="http://www.jstor.org/stable/2310780">On the Number of Partitionings of a Set of n Distinct Objects</a>, Amer. Math. Monthly 69 (1962), no. 8, 782--785. MR1531841. %H A011967 Cohn, Martin; Even, Shimon; Menger, Karl, Jr.; Hooper, Philip K.; <a href="/A011965/a011965.pdf">On the Number of Partitionings of a Set of n Distinct Objects</a>, Amer. Math. Monthly 69 (1962), no. 8, 782--785. MR1531841. [Annotated scanned copy] %H A011967 Jocelyn Quaintance and Harris Kwong, <a href="http://www.emis.de/journals/INTEGERS/papers/n29/n29.Abstract.html">A combinatorial interpretation of the Catalan and Bell number difference tables</a>, Integers, 13 (2013), #A29. %t A011967 Differences[BellB[Range[0, 50]], 4] (* _Vladimir Joseph Stephan Orlovsky_, May 25 2011 *) %o A011967 (Python) %o A011967 # requires python 3.2 or higher. Otherwise use def'n of accumulate in python docs. %o A011967 from itertools import accumulate %o A011967 A011967_list, blist, b = [4], [5, 7, 10, 15], 15 %o A011967 for _ in range(250): %o A011967 blist = list(accumulate([b]+blist)) %o A011967 b = blist[-1] %o A011967 A011967_list.append(blist[-5]) # _Chai Wah Wu_, Sep 20 2014 %Y A011967 Cf. A000110, A005493, A011965, A011966, A106436. %K A011967 nonn %O A011967 0,1 %A A011967 _N. J. A. Sloane_