|
Search: id:A085865
|
|
|
| A085865 |
|
a(1) = 2, a(n+1) = a(n)*{sigma(a(n))}, where sigma(n) is the sum of the divisors function. |
|
+0
2
|
|
| 2, 6, 72, 14040, 707616000, 2299654269739008000, 25353370781704805143366427867873280000, 3361021040447648920437074194752848938805829494939344230020451929790873600000
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
a(1) = 1, a(n+1) = a(n) + sigma(a(n)) gives A081973.
|
|
EXAMPLE
|
a(3) = 72 and sigma(72)= 195, hence a(4) = 72*195 = 14040.
|
|
PROGRAM
|
(PARI) for(n=1, 9, if(n==1, a=2, a*=sigma(a)); print(a); )
|
|
CROSSREFS
|
Cf. A064491, A081973, A085864.
Sequence in context: A052613 A156493 A117515 this_sequence A061296 A019993 A065410
Adjacent sequences: A085862 A085863 A085864 this_sequence A085866 A085867 A085868
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 06 2003
|
|
EXTENSIONS
|
More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jul 16 2003
|
|
|
Search completed in 0.002 seconds
|
