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 A370553 #9 Feb 22 2024 17:46:35
%S A370553 1,3,5,5,19,35,331,65,18265,4433,141349,18863,1035215,14705,9158903,
%T A370553 6702403,-34376687,-21392575,-33594289475,-2206770805,-4905856636525,
%U A370553 -617315066615,-1713253866399725,-551582580432325,-51270656805872335,-180184164588301,-1630191679256007299
%N A370553 a(n) is the numerator of the imaginary part of Product_{k=1..n} (1 + i/k) where i is the imaginary unit.
%F A370553 a(n) = numerator of A231531(n)/n!. - _Chai Wah Wu_, Feb 22 2024
%e A370553 See A370551.
%o A370553 (PARI) a370553(n) = numerator(imag(prod(k=1, n, 1+I/k)))
%o A370553 (Python)
%o A370553 from math import factorial, gcd
%o A370553 from sympy.functions.combinatorial.numbers import stirling
%o A370553 def A370553(n): return (a:=sum(stirling(n+1,k<<1,kind=1)*(1 if k&1 else -1) for k in range((n+1>>1)+1)))//gcd(a,factorial(n)) # _Chai Wah Wu_, Feb 22 2024
%Y A370553 Cf. A231531, A370551, A370552, A370554.
%K A370553 frac,sign,easy
%O A370553 1,2
%A A370553 _Hugo Pfoertner_, Feb 22 2024