|
|
A080473
|
|
a(n)= sum of the products of taking (n-1) numbers from the next n numbers. The next n numbers can be grouped like this (1), (2,3), (4,5,6), (7,8,9,10),... and a(n) is the (sum of the reciprocals of all members) multiplied by (the product of all members).
|
|
1
|
|
|
1, 5, 74, 2414, 140274, 12780984, 1681732464, 301837526640, 70870658200560, 21085710340560480, 7752245316736838400, 3451176556978487944320, 1829509243576458084345600, 1138750671753488468994278400
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
a(3)= 74. The third group of next n numbers is (4,5,6) and a(3) = 4*5 + 5*6+ 4*6= 74.
|
|
CROSSREFS
|
|
|
KEYWORD
|
hard,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003
|
|
STATUS
|
approved
|
|
|
|