

A191871


a(n) = Numerator(n^2 / 2^n).


3



0, 1, 1, 9, 1, 25, 9, 49, 1, 81, 25, 121, 9, 169, 49, 225, 1, 289, 81, 361, 25, 441, 121, 529, 9, 625, 169, 729, 49, 841, 225, 961, 1, 1089, 289, 1225, 81, 1369, 361, 1521, 25, 1681, 441, 1849, 121, 2025, 529, 2209, 9, 2401, 625, 2601, 169, 2809, 729, 3025
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OFFSET

0,4


COMMENTS

Interesting Plot: ListPlot[Table[f[n], {n, 0, 10000, 2}]]
a(n+1) = largest odd divisor of A000290(n+1).  Jeremy Gardiner, Aug 25 2013
In binary, remove all trailing zeros, then square.  Ralf Stephan, Aug 26 2013
A fractal sequence. The oddnumbered elements give the odd squares A016754. If these elements are removed, the original sequence is recovered.  Jeremy Gardiner, Sep 14 2013


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..5000
Index entries for sequences related to binary expansion of n


FORMULA

a(n) = A000265(n^2) = A000265(n)^2.  M. F. Hasler, Jun 19 2011
Recurrence: a(2n) = a(n), a(2n+1) = (2n+1)^2.  Ralf Stephan, Aug 26 2013


MATHEMATICA

f[n_] := Numerator[n^2/2^n]; Table[f[n], {n, 0, 200, 2}]


PROG

(PARI) a(n)=(n>>valuation(n, 2))^2 \\ Charles R Greathouse IV & M. F. Hasler, Jun 19 2011


CROSSREFS

Sequence in context: A013616 A205381 A237587 * A181318 A202006 A195278
Adjacent sequences: A191868 A191869 A191870 * A191872 A191873 A191874


KEYWORD

nonn,frac,easy,less


AUTHOR

Vladimir Joseph Stephan Orlovsky, Jun 18 2011


STATUS

approved



