A220449 Define u(n) as in A220448; then a(1)=1, thereafter a(n) = u(n)*a(n-1).
1, 1, -10, 10, 190, -730, -6620, 55900, 365300, -5864300, -28269800, 839594600, 2691559000, -159300557000, -238131478000, 38894192662000, -15194495654000, -11911522255750000, 29697351895900000, 4477959179352100000, -21683886333440500000, -2029107997508660900000, 15145164178973569000000
Offset: 1
Keywords
Links
- N. J. A. Sloane, Table of n, a(n) for n = 1..100
- V. H. Moll, An arithmetic conjecture on a sequence of arctangent sums, 2012. See f_n.
Programs
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Maple
x:=proc(n) option remember; if n=1 then 1 else (x(n-1)+n)/(1-n*x(n-1)); fi; end; f:=proc(n) option remember; global x; if n = 1 then 1 else n*x(n-1)*f(n-1)-f(n-1); fi; end; [seq(f(n),n=1..30)];
Comments