OFFSET
1,1
REFERENCES
Brualdi, Richard A. and Ryser, Herbert J., Combinatorial Matrix Theory, Cambridge NY (1991), Chapter 7.
LINKS
Indranil Ghosh, Table of n, a(n) for n = 1..445
Seok-Zun Song et al., Extremes of permanents of (0,1)-matrices, Lin. Algebra and its Applic. 373 (2003), pp. 197-210.
FORMULA
a(n) = (n+3)*a(n-1) + (n-2)*a(n-2), a(1)=5, a(2)=25.
a(n) ~ exp(-1) * n! * n^4 / 24. - Vaclav Kotesovec, Nov 30 2017
MATHEMATICA
f[x_] := x*HypergeometricPFQ[{1, 5}, {}, x/(x+1)]/(x+1); Total /@ Partition[ CoefficientList[ Series[f[x], {x, 0, 18}], x], 2, 1] // Rest (* Jean-François Alcover, Nov 12 2013, after A001909 and Mark van Hoeij *)
t={5, 25}; Do[AppendTo[t, (n+3)*t[[-1]]+(n-2)*t[[-2]]], {n, 3, 17}]; t (* Indranil Ghosh, Feb 21 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jaap Spies, Dec 13 2003
EXTENSIONS
Corrected by Jaap Spies, Jan 26 2004
STATUS
approved