OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..250
FORMULA
G.f.: A(x) = exp( Sum_{n>=1} A000275(n)*x^n/n ) where A000275 is the number of pairs of permutations with rise/rise forbidden.
a(n) ~ c * n! * (n-1)! / r^n, where r = 1/4*BesselJZero[0,1]^2 = 1.44579649073669613 and c = 1/(sqrt(r) * BesselJ(1, 2*sqrt(r))) = 1.6019746969280466266484... - Vaclav Kotesovec, Mar 02 2014, updated Apr 01 2018
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 8*x^3 + 61*x^4 + 797*x^5 + 16021*x^6 +...
log(A(x)) = x + 3*x^2/2 + 19*x^3/3 + 211*x^4/4 + 3651*x^5/5 + 90921*x^6/6 +...+ A000275(n)*x^n/n +...
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Apr 01 2011
STATUS
approved