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Search: id:A046652
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| A046652 |
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Triangle of rooted planar maps, read by rows. |
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+0
3
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| 1, 2, 2, 3, 8, 7, 4, 21, 34, 30, 5, 44, 114, 160, 143, 6, 80, 308, 609, 806, 728, 7, 132, 715, 1908, 3315, 4256, 3876, 8, 203, 1482, 5185, 11420, 18444, 23256, 21318, 9, 296, 2814, 12600, 34520, 67856, 104652, 130416, 120175, 10, 414, 4984, 27965, 93924, 221300, 404016, 603801, 746350, 690690, 11, 560, 8343, 57584, 234066, 654336, 1394505, 2418372, 3533145, 4341480, 4032015
(list; table; graph; listen)
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OFFSET
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0,2
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REFERENCES
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W. G. Brown, Enumeration of non-separable planar maps, Canad. J. Math., 15 (1963), 526-545.
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EXAMPLE
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Triangle begins:
1,
2,2,
3,8,7,
4,21,34,30,
5,44,114,160,143,
6,80,308,609,806,728,
...
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MAPLE
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T := proc(n, k) if k<=n then k*sum((2*j-k+1)*(j-1)!*(3*n-k-j)!/(j-k+1)!/(j-k)!/(2*k-j-1)!/(n-j)!, j=k..min(n, 2*k-1))/(2*n-k+1)! else 0 fi end: seq(seq(T(n, n-k+1), k=1..n), n=1..11); - Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 30 2008
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CROSSREFS
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A091665 is the same triangle with rows reversed and has much more information.
Sequence in context: A069830 A153935 A153944 this_sequence A091681 A076541 A159789
Adjacent sequences: A046649 A046650 A046651 this_sequence A046653 A046654 A046655
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KEYWORD
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tabl,nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 30 2008
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