A354479 a(n) is the denominator of Sum_{k=1..n} 1 / Stirling1(n,k).
1, 1, 6, 33, 4200, 4192200, 5115600, 545250747888, 10086416728304192640, 126556188275836361347200, 451535899566923284351392000, 250606479905655959999200124455664175360, 1493469115548888160803495265626573200563200, 47083781674990641531154175811928872812783834939059200
Offset: 1
Examples
1, 0, 7/6, 25/33, 3991/4200, 3923773/4192200, 4901627/5115600, 527165212865/545250747888, ...
Programs
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Mathematica
Table[Sum[1/StirlingS1[n, k], {k, 1, n}], {n, 1, 14}] // Denominator -
PARI
a(n) = denominator(sum(k=1, n, 1/stirling(n, k, 1))); \\ Michel Marcus, Jun 02 2022