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 A326501 #28 Jun 18 2022 12:13:25
%S A326501 1,0,4,-23,233,-2892,43764,-779779,15997437,-371423052,9628576948,
%T A326501 -275683093663,8640417354593,-294234689237660,10817772136320356,
%U A326501 -427076118244539019,18019667955465012597,-809220593930871751580,38537187481365665823844
%N A326501 a(n) = Sum_{k=0..n} (-k)^k.
%H A326501 Seiichi Manyama, <a href="/A326501/b326501.txt">Table of n, a(n) for n = 0..386</a>
%F A326501 a(n) = 1 + (-1)^n * A001099(n).
%p A326501 a:= proc(n) option remember; `if`(n<0, 0, (-n)^n+a(n-1)) end:
%p A326501 seq(a(n), n=0..23); # _Alois P. Heinz_, Sep 12 2019
%t A326501 RecurrenceTable[{a[0] == 1, a[n] == a[n-1] + (-n)^n}, a, {n, 0, 23}] (* _Jean-François Alcover_, Nov 27 2020 *)
%o A326501 (PARI) {a(n) = sum(k=0, n, (-k)^k)}
%o A326501 (Python)
%o A326501 from itertools import accumulate, count, islice
%o A326501 def A326501_gen(): # generator of terms
%o A326501 yield from accumulate((-k)**k for k in count(0))
%o A326501 A326501_list = list(islice(A326501_gen(),10)) # _Chai Wah Wu_, Jun 18 2022
%Y A326501 Cf. A001099, A062970, A177885.
%K A326501 sign,easy
%O A326501 0,3
%A A326501 _Seiichi Manyama_, Sep 12 2019