A074189 a(1) = 1, a(2) = 2; for n > 2, a(n) = {a(n-1) +a(n+1)}/n or a(n+1) = n*a(n)-a(n-1).

-1, 1, 2, 3, 7, 25, 118, 683, 4663, 36621, 324926, 3212639, 35014103, 416956597, 5385421658, 74978946615, 1119298777567, 17833801494457, 302055326628202, 5419162077813179

Offset

0,3

Links

Table of n, a(n) for n=0..19.

Formula

a(n+2) = (n+1)*a(n+1)-a(n); a(0) = -1, a(1) = 1; a(2) = 2. G.f. A(x) = sum(a(n)*x^n) is a solution of the differential equation (x^2)*A'(x)-(1+x^2)*A(x) = 1-x - Bruce Corrigan (scentman(AT)myfamily.com), Oct 19 2002

Example

a(6) = 5*a(5)-a(4) = 5*25-7 = 118.

Crossrefs

Sequence in context: A308161 A094697 A095910 * A301317 A325125 A091230

Adjacent sequences: A074186 A074187 A074188 * A074190 A074191 A074192

Keyword

sign

Author

Amarnath Murthy, Sep 20 2002

Extensions

More terms from Bruce Corrigan (scentman(AT)myfamily.com), Oct 19 2002

Status

approved