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%I #19 Sep 08 2022 08:46:04
%S 1,2,6,31,256,2960,44169,813298,17952898,465148507,13915349132,
%T 474372594032,18228772272441,782443669319410,37224994809379094,
%U 1949799331997896119,111783178753323665728,6978369826387194664144,472207139326449254997425
%N Sum of squares of Bell numbers (A000110).
%F a(n) = Sum_{k=0..n} Bell(k)^2.
%t Accumulate[BellB[Range[0, 20]]^2] (* _Bruno Berselli_, Sep 27 2012 *)
%o (Maxima) makelist(sum(belln(k)^2,k,0,n),n,0,30);
%o (Magma) [&+[Bell(i)^2: i in [0..n]]: n in [0..20]]; // _Bruno Berselli_, Sep 27 2012
%o (Python)
%o from itertools import accumulate, islice
%o def A217143_gen(): # generator of terms
%o yield 1
%o blist, b, c = (1,), 1, 1
%o while True:
%o blist = list(accumulate(blist, initial=(b:=blist[-1])))
%o yield (c := c+b**2)
%o A217143_list = list(islice(A217143_gen(),20)) # _Chai Wah Wu_, Jun 22 2022
%Y Cf. A000110, A005001, A087650, A217144.
%Y Partial sums of A001247.
%K nonn
%O 0,2
%A _Emanuele Munarini_, Sep 27 2012
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