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 A122033 a(n) = 2*a(n-1) - 2*(n-2)*a(n-2), with a(0)=1, a(1)=2. 2
 1, 2, 4, 4, -8, -40, -16, 368, 928, -3296, -21440, 16448, 461696, 561536, -9957632, -34515200, 209783296, 1455022592, -3803020288, -57076808704, 22755112960, 2214428956672, 3518653394944, -85968709390336, -326758168158208, 3301044295639040, 22286480662872064 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..725 FORMULA a(n) = 2*a(n-1) - 2*(n-2)*a(n-2), with a(0)=1, a(1)=2. - G. C. Greubel, Oct 04 2019 a(n) = 2*A062267(n-1) for n > 0. - Michel Marcus, Oct 05 2019 E.g.f.: 1 + exp(1)*sqrt(Pi)*( erf(1) - erf(1-x) ), where erf(x) is the error function. - G. C. Greubel, Oct 05 2019 MAPLE a:= proc(n) option remember;       if n < 2 then n+1     else 2*(a(n-1) - (n-2)*a(n-2))       fi     end proc: seq(a(n), n = 0..35); # G. C. Greubel, Oct 04 2019 MATHEMATICA a[n_]:= a[n]= If[n<2, n+1, a[n-1]-(n-2)*a[n-2]]; Table[a[n], {n, 0, 30}] (* modified by G. C. Greubel, Oct 04 2019 *) PROG (PARI) my(m=35, v=concat([1, 2], vector(m-2))); for(n=3, m, v[n] = 2*(v[n-1] - (n-3)*v[n-2] ) ); v \\ G. C. Greubel, Oct 04 2019 (MAGMA) I:=[1, 2]; [n le 2 select I[n] else 2*(Self(n-1)-(n-3)*Self(n-2)): n in [1..35]]; // G. C. Greubel, Oct 04 2019 (Sage) def a(n):     if n<2: return n+1     else: return 2*(a(n-1) - (n-2)*a(n-2)) [a(n) for n in (0..35)] # G. C. Greubel, Oct 04 2019 (GAP) a:=[1, 2];; for n in [3..35] do a[n]:=2*(a[n-1]-(n-3)*a[n-2]); od; a; # G. C. Greubel, Oct 04 2019 CROSSREFS Cf. A000898, A121966, A328141. Sequence in context: A296229 A322175 A298117 * A281122 A201777 A096189 Adjacent sequences:  A122030 A122031 A122032 * A122034 A122035 A122036 KEYWORD sign,less AUTHOR Roger L. Bagula, Sep 13 2006 EXTENSIONS Edited by N. J. A. Sloane, Sep 17 2006 Corrected and offset changed by G. C. Greubel, Oct 04 2019 STATUS approved

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Last modified August 8 16:31 EDT 2022. Contains 356016 sequences. (Running on oeis4.)