This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A048139 Number of planar partitions of n, when partitions that are rotations of each other (when regarded as 3-D objects) are counted only once. 1
 1, 1, 2, 5, 8, 16, 30, 54, 94, 168, 287, 493, 831, 1391, 2293, 3769, 6114, 9867, 15782, 25098, 39598, 62165, 96935, 150398, 232021, 356261, 544220, 827758, 1253222, 1889655, 2837455, 4244505, 6324993, 9392009, 13897056, 20494991, 30126628 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Plane partitions seen as 3-dimensional-objects can have a threefold symmetry axis. LINKS EXAMPLE n=3 gives 2 forms: {{3}}={{1,1,1}}={{1},{1},{1}} and {{2,1}}={{1,1},{1}}={{2},{1}}. CROSSREFS Equals Cs + 2 C1 + 2 C3 + C3v, Cs=A000784, C1=A000785, C3=A048142, C3v=A048141. Cf. A000219, A005987. Or, equals (2*A048141+A000219+4*A048142)/3. Sequence in context: A026530 A032254 A048237 * A071085 A240951 A280373 Adjacent sequences:  A048136 A048137 A048138 * A048140 A048141 A048142 KEYWORD nonn AUTHOR EXTENSIONS Edited by N. J. A. Sloane, Oct 26 2008 at the suggestion of R. J. Mathar. 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.

Last modified January 17 14:12 EST 2019. Contains 319225 sequences. (Running on oeis4.)