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 A045748 #23 Mar 22 2021 20:04:48
%S A045748 3,13,313,313,40313,940313,940313,20940313,420940313,420940313,
%T A045748 20420940313,920420940313,8920420940313,28920420940313,
%U A045748 528920420940313,6528920420940313,36528920420940313,336528920420940313,2336528920420940313,42336528920420940313
%N A045748 a(n) is the number consisting of the last n digits (although any leading 0's among those last n digits are omitted) of Sum_{j=1..k} j! for all sufficiently large k.
%F A045748 a(n) = (Sum_{k>=1} k!) mod 10^n. - _Sean A. Irvine_, Mar 19 2021
%e A045748 Look at A007489, the partial sums of the factorials. The last digit stabilizes at 3, so a(1) = 3. The last two digits stabilize at 13, so a(2) = 13. - _N. J. A. Sloane_, Mar 22 2021
%Y A045748 Cf. A007489, A082648.
%K A045748 nonn,base
%O A045748 1,1
%A A045748 _Jeff Burch_