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.
[Numerator(Factorial(n)/10^n): n in [0..30]];
Table[Numerator[n!/10^n], {n, 0, 30}]
[Denominator(Factorial(n)/10^n): n in [0..30]];
Table[Denominator[n!/10^n], {n, 0, 30}]
Table starts: [0] 1; [1] 0, 1; [2] 0, 2, 2; [3] 0, 3, 9, 6; [4] 0, 4, 24, 48, 24; [5] 0, 5, 50, 200, 300, 120; [6] 0, 6, 90, 600, 1800, 2160, 720; [7] 0, 7, 147, 1470, 7350, 17640, 17640, 5040; [8] 0, 8, 224, 3136, 23520, 94080, 188160, 161280, 40320; [9] 0, 9, 324, 6048, 63504, 381024, 1270080, 2177280, 1632960, 362880;
T := (n, k) -> ifelse(k = 0, k^n, binomial(n, k)^2 * k! / (n - k + 1)): seq(seq(T(n, k), k = 0..n), n = 0..9);
T[n_, 0] := Boole[n == 0]; T[n_, k_] := Binomial[n, k]^2 * k!/(n - k + 1); Table[T[n, k], {n, 0, 9}, {k, 0, n}] // Flatten (* Amiram Eldar, Jan 09 2022 *)
seq(floor(n*n!/2 + 1), n=1..20);
a[n_] := Floor[n*n!/2 + 1]; Array[a, 20] (* Amiram Eldar, May 09 2025 *)
a(n) = (n*n!)\2 + 1; \\ Amiram Eldar, May 09 2025
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