|
|
A185265
|
|
a(0)=1, a(1)=2; thereafter a(n) = f(n-1) + f(n-2) where f() = A164387().
|
|
2
|
|
|
1, 2, 3, 6, 12, 22, 39, 70, 127, 231, 419, 759, 1375, 2492, 4517, 8187, 14838, 26892, 48739, 88335, 160099, 290164, 525894, 953132, 1727460, 3130855, 5674373, 10284254, 18639219, 33781788, 61226235, 110966650, 201116358, 364504015, 660628396, 1197325296, 2170036700, 3932982369, 7128151480
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
Arises in studying lunar arithmetic.
|
|
LINKS
|
D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
|
|
FORMULA
|
Satisfies the same recurrence as A164387 and A079976, although with different initial conditions.
a(n) = a(n-1) + a(n-2) + a(n-4) + a(n-5) for n>5.
G.f.: -(x+1)*(x^4+x^3+1) / (x^5+x^4+x^2+x-1). (End)
|
|
MATHEMATICA
|
CoefficientList[Series[-(x + 1)*(x^4 + x^3 + 1)/(x^5 + x^4 + x^2 + x - 1), {x, 0, 50}], x] (* G. C. Greubel, Jun 25 2017 *)
|
|
PROG
|
(PARI) x='x+O('x^50); Vec(-(x+1)*(x^4+x^3+1)/(x^5+x^4+x^2+x-1)) \\ G. C. Greubel, Jun 25 2017
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|