|
|
A084737
|
|
Beginning with 1, numbers such that (a(n+2)-a(n+1))/(a(n+1)-a(n)) = prime(n).
|
|
1
|
|
|
1, 2, 4, 10, 40, 250, 2560, 32590, 543100, 10242790, 233335660, 6703028890, 207263519020, 7628001653830, 311878265181040, 13394639596851070, 628284422185342480, 33217442899375387210, 1955977793053588026280
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Successive differences are primorials.
|
|
LINKS
|
|
|
FORMULA
|
For n >= 2, a(n) = 1 + A143293(n-2).
For n >= 3, a(n) = 2 + A060389(n-2).
(End)
|
|
EXAMPLE
|
a(3) = 4, a(4) = 10 and a(5) = 40 and (40-10)/(10-4) = 5 = prime(3).
|
|
MATHEMATICA
|
Join[{1}, Accumulate[FoldList[Times, 1, Prime[Range[20]]]]+1] (* Harvey P. Dale, Dec 14 2011 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 14 2003
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|