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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

Table of n, a(n) for n=1..14.

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

Cf. A080474.

Sequence in context: A126740 A251666 A192564 * A266570 A156703 A285452

Adjacent sequences:  A080470 A080471 A080472 * A080474 A080475 A080476

KEYWORD

hard,nonn

AUTHOR

Amarnath Murthy, Mar 11 2003

EXTENSIONS

Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003

STATUS

approved

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Last modified July 23 00:43 EDT 2019. Contains 325228 sequences. (Running on oeis4.)