login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A073642 Replace 2^k in the binary representation of n with k (i.e., if n = 2^a + 2^b + 2^c + ... then a(n) = a + b + c + ...). 11
0, 0, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 6, 6, 4, 4, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 10, 10, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 10, 10, 11, 11, 9, 9, 10, 10, 11, 11, 12, 12, 12, 12, 13, 13, 14, 14, 15, 15, 6, 6, 7, 7, 8, 8, 9, 9, 9, 9, 10, 10, 11, 11, 12, 12, 10, 10, 11, 11, 12, 12, 13, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

For n >= 1, a(n) is the n-th row sum of the irregular triangle A133457. - Vladimir Shevelev, Dec 14 2015

For n >= 0, 2^a(n) is the number of partitions of n whose dimension (given by the hook-length formula) is an odd integer. See the Macdonald reference. - Arvind Ayyer, May 12 2016

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Arvind Ayyer, Amritanshu Prasad, Steven Spallone, Odd partitions in Young's lattice, arXiv:1601.01776 [math.CO], 2016.

Ian G. Macdonald, On the degrees of the irreducible representations of symmetric groups, Bulletin of the London Mathematical Society, 3(2):189-192, 1971.

FORMULA

It seems that for n > 10 a(n) < n/(2*log(n)) and that Sum_{k=1..n} a(k) is asymptotic to C*n*log(n)^2 with 1/2 > C > 0.47.

a(1)=0, a(2n) = a(n) + e1(n), a(2n+1) = a(2n), where e1(n) = A000120(n). - Ralf Stephan, Jun 19 2003

a(n) = if n=2^log2(n) then log2(n) else log2(n)+a(n-2^log2(n)), where log2=A000523. a(2*n+1) = a(2*n), as 2^0 = 1. - Reinhard Zumkeller, Aug 17 2003

a(n) = Sum_{k=0..A070939(n)-1} k*A030308(n,k). - Reinhard Zumkeller, Jun 01 2013

Conjecture: a(n) = (3*A011371(n) - Sum_{k=1..n} A007814(k)^2)/2 for n > 0. - Velin Yanev, Sep 09 2017

EXAMPLE

9 = 2^3 + 2^0, hence a(9) = 3 + 0 = 3;

25 = 2^4 + 2^3 + 2^0, hence a(25) = 4 + 3 + 0 = 7.

MAPLE

A073642 := proc(n)

        local bdgs ;

        bdgs := convert(n, base, 2) ;

        add( op(i, bdgs)*(i-1), i=1..nops(bdgs)) ;

end proc: # R. J. Mathar, Nov 17 2011

MATHEMATICA

Total[Flatten[Position[Rest[Reverse[IntegerDigits[#, 2]]], 1]]] & /@ Range[0, 87] (* Jayanta Basu, Jul 03 2013 *)

PROG

(PARI) a(n)=sum(i=1, length(binary(n)), component(binary(n), i)*(length(binary(n))-i))

(Haskell)

a073642 = sum . zipWith (*) [0..] . a030308_row

-- Reinhard Zumkeller, Jun 01 2013

CROSSREFS

a(n) = log_2(A059867(n)).

Cf. A059867, a(n) = A029931(floor(n/2)).

Cf. A087135, A000009, A087136.

Cf. A272090

Sequence in context: A225644 A225633 A060960 * A262869 A108356 A239499

Adjacent sequences:  A073639 A073640 A073641 * A073643 A073644 A073645

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Aug 29 2002

EXTENSIONS

a(0)=0 and offset corrected by Philippe Deléham, Apr 20 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 23 18:13 EDT 2019. Contains 321433 sequences. (Running on oeis4.)