OFFSET
0,4
LINKS
Robert Israel, Table of n, a(n) for n = 0..426
FORMULA
From Wolfdieter Lang, Jun 07 2017: (Start)
G.f. of {r(n)}_{n>=0}: x*exp(-x/2)/(1-x)^(3/2).
a(n) = numerator(r(n)). See the name for the recurrence of r(n). (End)
MAPLE
R[0]:= 0: R[1]:= 1: A[0]:= 0: A[1]:= 1:
for n from 2 to 30 do
R[n]:= R[n-1] + R[n-2]/(2*(n-1));
A[n]:= numer(R[n]);
od:
seq(A[i], i=0..30); # Robert Israel, May 25 2017
MATHEMATICA
Numerator[RecurrenceTable[{r[n] == r[n - 1] + r[n - 2]/(2 (n - 1)), r[0] == 0, r[1] == 1}, r, {n, 0, 25}]]
PROG
(PARI) a(n) = if(n < 2, return(n)); n++; my(v=vector(n)); v[1]=0; v[2] = 1; for(i = 3, n, v[i] = v[i-1] + v[i-2]/(2*i - 4)); numerator(v[#v]) \\ David A. Corneth, May 14 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Terry D. Grant, May 05 2017
EXTENSIONS
Name changed, a(0) and a(1) added by David A. Corneth, May 14 2017
a(20)-a(22) from David A. Corneth, May 21 2017
Name corrected by Robert Israel, May 25 2017
STATUS
approved