|
|
A054766
|
|
a(n+2) = (2*n + 3)*a(n+1) + (n + 1)^2*a(n), a(0) = 1, a(1) = 0.
|
|
5
|
|
|
1, 0, 1, 5, 44, 476, 6336, 99504, 1803024, 37019664, 849418560, 21539756160, 598194037440, 18056575823040, 588622339549440, 20609136708249600, 771323264354361600, 30729606721005830400, 1298448658633614566400
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,4
|
|
COMMENTS
|
Numerators of the convergents of the generalized continued fraction expansion 4/Pi - 1 = [0; 1/3, 4/5, 9/7,..., n^2/(2*n + 1),...] = 1/(3 + 4/(5 + 9/(7 + ...))). The first 4 convergents are 1/3, 5/19, 44/160 and 476/1744.
|
|
LINKS
|
|
|
FORMULA
|
a(n) ~ (1 - Pi/4) * (1 + sqrt(2))^(n + 1/2) * n^n / (2^(1/4) * exp(n)). - Vaclav Kotesovec, Feb 18 2017
|
|
MATHEMATICA
|
RecurrenceTable[{a[n+2] == (2*n+3)*a[n+1] + (n+1)^2*a[n], a[0] == 1, a[1] == 0}, a, {n, 0, 25}] (* Vaclav Kotesovec, Feb 18 2017 *)
t={1, 0}; Do[AppendTo[t, (2(n-2)+3)*t[[-1]]+(n-1)^2*t[[-2]]], {n, 2, 18}]; t (* Indranil Ghosh, Feb 25 2017 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy,frac
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Definition expanded by Al Hakanson (hawkuu(AT)gmail.com), Dec 01 2008
|
|
STATUS
|
approved
|
|
|
|