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A089709 a(1) = 1, a(2) = 2; for n>2, a(n) = sum_{r=1..n} {sum of all previous terms taken r at a time}. 1
1, 2, 6, 36, 360, 6480, 220320, 14541120, 1890345600, 487709164800, 250682510707200, 257200255985587200, 527260524770453760000, 2160713630509319508480000, 17704887488393364052485120000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..15.

FORMULA

a(n)=(2^(n-2)+2)*a(n-1), n>3. - Vladeta Jovovic, Nov 17 2003

EXAMPLE

a(4) = [{a(1)} + {a(2)} + {a(3)}] + [{(a(1) + a(2)} + {a(1) + a(3)} + { a(2) + a(3)}] + [{a(1) + a(2) + a(3)}] = 36.

CROSSREFS

Cf. A089985.

Sequence in context: A133822 A133892 A196870 * A262234 A055512 A078973

Adjacent sequences:  A089706 A089707 A089708 * A089710 A089711 A089712

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Nov 14 2003

EXTENSIONS

More terms from Ray Chandler, Nov 21 2003

STATUS

approved

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Last modified May 27 06:24 EDT 2019. Contains 323599 sequences. (Running on oeis4.)