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 A142722 a(0)=a(1)=1 and a(n) = -(2*n-1)*a(n-1) + a(n-2) for n>=2. 0
 1, 1, -2, 11, -79, 722, -8021, 104995, -1582946, 27015077, -514869409, 10839272666, -249818140727, 6256292790841, -169169723493434, 4912178274100427, -152446696220606671, 5035653153554120570, -176400307070614826621, 6531847014766302705547 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS MAPLE a:= proc(n) if n<2 then 1 else a(n) := -(2*n-1)*a(n-1) + a(n-2) fi end: seq (a(n), n=0..25);   # Sergei N. Gladkovskii, Jul 04 2012 MATHEMATICA k = 2; b[0] = 1; b[n_] := b[n] = b[n - 1] + k M[0] := {{-b[n], -1}, {1, 0}}; M[1] := {{-b[n], 1}, {-1, 0}}; v[0] = {1, 1}; v[n_] := v[n] = M[Mod[n, 2]].v[n - 1]; Table[v[n][[1]], {n, 1, 30}] PROG (PARI) a(n)= if ( n<=1, 1, -(2*n-1)*a(n-1) + a(n-2) ); /* note this is inefficient, optimize using memoization: */ v=vector(66); v[1]=1; v[2]=1; /* PARI's vectors are one-based */ for (n=3, #v, v[n] = -(2*n-3)*v[n-1] + v[n-2]); v /* show terms */ /* Joerg Arndt, Jul 023 2012 */ CROSSREFS Sequence in context: A154273 A253256 A163203 * A099661 A027110 A118969 Adjacent sequences:  A142719 A142720 A142721 * A142723 A142724 A142725 KEYWORD sign AUTHOR Roger L. Bagula and Gary W. Adamson, Sep 27 2008 STATUS approved

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Last modified August 23 17:13 EDT 2017. Contains 291020 sequences.