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 A341330 #9 Feb 18 2021 16:13:32
%S A341330 1,-7,74,-950,14675,-265261,5499540,-128718188,3358066213,
%T A341330 -96641933787,3041786442934,-103951418936138,3833424966763151,
%U A341330 -151734670591049073,6416673685121841552,-288731231494230984304,13774353220573494006705,-694460992134764182350927
%N A341330 a(n) = Sum_{k=1..n} (-k)^(k+1).
%t A341330 Accumulate[(-#)^(#+1)&/@Range[17]]
%o A341330 (PARI) a(n) = sum(i=1, n, (-i)^(i+1));
%o A341330 (Python)
%o A341330 sum = 0
%o A341330 for i in range(1,20):
%o A341330 sum += (-i)**(i+1)
%o A341330 print(sum, end = ", ")
%Y A341330 Cf. A007778, A062815.
%K A341330 sign
%O A341330 1,2
%A A341330 _John H. Chakkour_, Feb 09 2021