|
Search: id:A133324
|
|
|
| A133324 |
|
7-gonal numbers which are sum of 2 consecutive 7-gonal numbers. |
|
+0
1
|
|
| 1, 144841, 927821665, 222590743768705, 1425873367156486249, 342076743178546829707489
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
We write 2.5*p^2-1.5*p=(2.5*r^2-1.5*r)+2.5*(r+1)^2-1.5*(r+1) ; X=10*p-3 and Y=10*r+2 satisfy the Diophantine equation X^2=2*Y^2+41.
|
|
FORMULA
|
The bisections modulo satisfy the same recurrence relation a(n+2)=1536796802*a(n+1)-a(n)-441829080
|
|
EXAMPLE
|
a(2)=2.5*241^2-1.5*241=144841=5*r^2+4*r+1 with r=170
|
|
CROSSREFS
|
Sequence in context: A146754 A004042 A145742 this_sequence A110084 A004670 A111044
Adjacent sequences: A133321 A133322 A133323 this_sequence A133325 A133326 A133327
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
R. Choulet (richardchoulet(AT)yahoo.fr), Oct 18 2007
|
|
|
Search completed in 0.002 seconds
|
