|
Search: id:A004981
|
|
|
| A004981 |
|
(2^n/n!)*product[ k=0..n-1 ](4*k + 1). |
|
+0
6
|
|
| 1, 2, 10, 60, 390, 2652, 18564, 132600, 961350, 7049900, 52169260, 388898120, 2916735900, 21987701400, 166478310600, 1265235160560, 9647418099270, 73774373700300, 565603531702300, 4346216612028200, 33465867912617140
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
The convolution of this sequence with itself yields A059304. - T. D. Noe (noe(AT)sspectra.com), Jun 11 2002
|
|
FORMULA
|
a(n) ~ Gamma(1/4)^-1*n^(-3/4)*2^(3*n)*{1 - 3/32*n^-1 - ...}
G.f.: (1-8x)^(-1/4).
A002897(n)=Sum_{k=0..n} a(k)^2*a(n-k)^2. - Michael Somos Jan 31 2007
|
|
PROGRAM
|
(PARI) a(n)=if(n<0, 0, prod(k=1, n, (8*k-6)/k))
{a(n)=if(n<0, 0, polcoeff( (1-8*x+x*O(x^n))^(-1/4), n))} /* Michael Somos Jan 31 2007 */
|
|
CROSSREFS
|
Sequence in context: A026161 A025188 A114620 this_sequence A137571 A098616 A082042
Adjacent sequences: A004978 A004979 A004980 this_sequence A004982 A004983 A004984
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
Joe Keane (jgk(AT)jgk.org)
|
|
EXTENSIONS
|
More terms from James A. Sellers (sellersj(AT)math.psu.edu), May 01 2000
|
|
|
Search completed in 0.002 seconds
|
