|
| |
|
|
A007751
|
|
Even bisection of A007750.
|
|
2
| |
|
|
0, 7, 120, 1921, 30624, 488071, 7778520, 123968257, 1975713600, 31487449351, 501823476024, 7997688167041, 127461187196640, 2031381306979207, 32374639724470680, 515962854284551681, 8223031028828356224
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
REFERENCES
| Mentioned in a problem on p. 334 of Two-Year College Math. Jnl., Vol. 25, 1994.
|
|
|
FORMULA
| G.f.: x(7+x)/((1-x)(1-16x+x^2)). a(n)=16a(n-1)-a(n-2)+8.
a(n)=-4/7+(2/7)*[8-3*sqrt(7)]^n+(2/7)*[8+3*sqrt(7)]^n+(1/14)*sqrt(7)*[8+3*sqrt(7)]^n-(1/14) *[8-3*sqrt(7)]^n*sqrt(7), with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Jun 19 2008
|
|
|
PROG
| (PARI) a(n)=local(w); w=8+3*quadgen(28); imag(w^n)+4*(real(w^n)-1)/7
|
|
|
CROSSREFS
| Cf. A007750, A007752.
Sequence in context: A192565 A171209 A092612 * A193785 A156955 A196796
Adjacent sequences: A007748 A007749 A007750 * A007752 A007753 A007754
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| John C. Hallyburton, Jr. [ hallyb(AT)vmsdev.enet.dec.com ].
|
|
|
EXTENSIONS
| Edited by Michael Somos, Jul 27, 2002
|
| |
|
|
