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A178244 Number of distinct transpositions of binary digits (0s and 1s) in n. 0
1, 1, 2, 1, 3, 3, 3, 1, 4, 6, 6, 4, 6, 4, 4, 1, 5, 10, 10, 10, 10, 10, 10, 5, 10, 10, 10, 5, 10, 5, 5, 1, 6, 15, 15, 20, 15, 20, 20, 15, 15, 20, 20, 15, 20, 15, 15, 6, 15, 20, 20, 15, 20, 15, 15, 6, 20, 15, 15, 6, 15, 6, 6, 1, 7, 21, 21, 35, 21, 35, 35, 35, 21, 35, 35, 35, 35, 35, 35, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..79.

FORMULA

a(n)= binomial ((A000120(n-1)+A023416(n-1)), A000120(n-1)).

EXAMPLE

a(0)=1 because 0 (or 0 written in base 2), a(1)=1 because 1 (or 1 written in base 2), a(3)= 2 (or 10 written in base 2) and (01,10)=distinct transpositions.

CROSSREFS

Cf. A001477.

Sequence in context: A124770 A099246 A039775 * A227532 A152534 A136018

Adjacent sequences:  A178241 A178242 A178243 * A178245 A178246 A178247

KEYWORD

nonn,base

AUTHOR

Juri-Stepan Gerasimov, May 23 2010

EXTENSIONS

Corrected (a 3 in the first group removed) by R. J. Mathar, May 28 2010

STATUS

approved

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Last modified November 26 05:57 EST 2014. Contains 250020 sequences.