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A131568 a(n)=sum in base 10 of numbers which in base 2 contain exactly n digits 1 and not more than n digits 0. 0
0, 3, 45, 630, 8925, 128898, 1891890 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..6.

FORMULA

a(n) = (2*n)!*(2^(2^n)-1)/(2*n!*n!)

EXAMPLE

For n=2 (11)b2 = (3)b10 (101)b2=(5)b10 (110)b2=(6)b10 (1100)b2=(12)b10 (1010)b2=(10)b10 (1001)b2=(9)b10 then a(2)=3+5+6+12+10+9=45

CROSSREFS

Sequence in context: A270064 A141445 A076140 * A287031 A124487 A266698

Adjacent sequences:  A131565 A131566 A131567 * A131569 A131570 A131571

KEYWORD

nonn,base

AUTHOR

Philippe LALLOUET (philip.lallouet(AT)wanadoo.fr), Aug 27 2007

STATUS

approved

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Last modified May 25 22:17 EDT 2019. Contains 323576 sequences. (Running on oeis4.)