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A163455 Number of terms in A163142 with n zeros in binary representation. 1
4, 36, 364, 3876, 42504, 475020, 5379616, 61523748, 708930508, 8217822536, 95722852680, 1119487075980, 13136858812224, 154603005527328, 1824010149372864, 21566576904406820, 255485622301674660 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

All terms are divisible by 4.

FORMULA

a(n)=(5n-1)!/(n!(4n-1)!).

EXAMPLE

a(1)=4 because there are 4 terms in A163142 with 1 zero in binary representation {23,27,29,30}_10 ={10111,11011,11101,11110}_2

a(2)=36 because there are 36 terms in A163142 with 2 zeros in binary representation: {639,703,735,751,759,763,765,766,831,863,879,887,891,893,894,927,943,951,955,957,958,975,983,987,989,990,999,1003,1005,1006,1011,1013,1014,1017,1018,1020}_10={1001111111,...,1111111100}_2

a(3)=364 terms in A163142 from 18431 to 32760 with 3 zeros in binary representation 18431_10=100011111111111_2 and 32760_10=111111111111000_2

a(4)=3876 terms in A163142 from 557055 to 1048560 with 4 zeros in binary representation, etc.

MATHEMATICA

Table[(5*n-1)!/ n!/(4*n-1)!, {n, 20}]

CROSSREFS

Sequence in context: A189334 A026334 A168595 * A138736 A198638 A019999

Adjacent sequences:  A163452 A163453 A163454 * A163456 A163457 A163458

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), Jul 28 2009

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Last modified February 17 02:48 EST 2012. Contains 205978 sequences.