OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..300
FORMULA
Conjecture: (n+2)*a(n) + 6*(-n-1)*a(n-1) + 12*(2*n+1)*a(n-2) + 32*(-n+1)*a(n-3) = 0. - R. J. Mathar, Mar 03 2013
a(n) ~ 8*sin(Pi*n/3+Pi/4) / (3^(3/4)*sqrt(Pi*n)) * 4^n. - Vaclav Kotesovec, Jul 30 2013
From Vladimir Reshetnikov, Nov 01 2015: (Start)
G.f.: 1/(6*x^2) + (2*x-1)/(6*x^2*sqrt(16*x^2-4*x+1)).
a(n) = 2*A012125(n+1)/(n+2).
(End)
MATHEMATICA
Table[ 2^(2n) JacobiP[ n, 1, 1, 1/2 ], {n, 0, 24} ]
Table[4^(n+1) (LegendreP[n+1, 1/2] - 2 LegendreP[n+2, 1/2])/3, {n, 0, 20}] (* Vladimir Reshetnikov, Nov 01 2015 *)
RecurrenceTable[{(n+2)*a[n] == 6*(n+1)*a[n-1] - 12*(2*n+1)*a[n-2] + 32*(n-1)*a[n-3], a[0] == 1, a[1] == 4, a[2] == 3}, a, {n, 0, 200}] (* G. C. Greubel, Nov 01 2015 *)
PROG
(PARI) a(n)=4^(n+1)*(pollegendre(n+1, 1/2) - 2*pollegendre(n+2, 1/2))/3 \\ Charles R Greathouse IV, Mar 18 2017
CROSSREFS
KEYWORD
sign
AUTHOR
EXTENSIONS
Sequence name by Wouter Meeussen, Mar 03 2013
STATUS
approved