A368853 a(n) = n! * (n+1)! * Sum_{k=0..n} (-1)^k/(k! * (k+1)!).
1, 1, 7, 83, 1661, 49829, 2092819, 117197863, 8438246137, 759442152329, 83538636756191, 11027100051817211, 1720227608083484917, 313081424671194254893, 65747099180950793527531, 15779303803428190446607439, 4291970634532467801477223409
Offset: 0
Programs
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PARI
a(n) = n!*(n+1)!*sum(k=0, n, (-1)^k/(k!*(k+1)!));
Formula
a(n) = n * (n+1) * a(n-1) + (-1)^n.
a(n) ~ BesselJ(1,2) * n! * (n+1)!. - Vaclav Kotesovec, Jan 08 2024