|
| |
|
|
A133324
|
|
7-gonal numbers which are sum of 2 consecutive 7-gonal numbers.
|
|
0
| | |
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| 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: A004042 A145742 A204641 * A204527 A110084 A004670
Adjacent sequences: A133321 A133322 A133323 * A133325 A133326 A133327
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| R. Choulet (richardchoulet(AT)yahoo.fr), Oct 18 2007
|
| |
|
|
