1,1

This is an unusual sequence mentioned on the Math Fun Mailing list. It does not quite fit the format of regular OEIS entries, but is too interesting to be forgotten. - N. J. A. Sloane, Mar 29 2009

The definition arises from the Fourier series for the Snowflake curve.

..................................................................

.............................. inf ...............................

.............................. ==== ............ m ...............

............................ k \ ....... %pi (k 2..- 5) ..... n ..

....................... (- 1).. > .. tan(--------------) (- 1) ...

............. inf ............ / ............ n + m ..............

............. ==== ........... ==== ........ 2 ...................

..... 5 m - 1 \ .............. n = 1 .............................

.. 3 2 ....... > ...... --------------------------------------- ..

............. / .................................... m ...........

............. ==== .......... m ... 3 ... 10 %pi (k 2 .- 5) ......

............. k = - inf . (k 2..- 5)..csc(-----------------) .....

................................................ 2 m .............

............................................... 2 ................

.. ------------------------------------------------------------ ..

........................... 3 ... 5 %pi ..........................

........................ %pi..csc(-----) .........................

................................... m ............................

.................................. 2 .............................

Sequence in context: A134753 A052481 A067897 this_sequence A099752 A081294 A004171

Adjacent sequences: A145679 A145680 A145681 this_sequence A145683 A145684 A145685

nonn

R. William Gosper (rwg(AT)osots.com), Apr 12 2005